j|j|j |j|f>jt B i li iiii wnii ai # « i« »i ii ^i w>i«)i 

i i > l iil nii !> itri^j ) 
•n'ri'i-oiiiinwinwii'iimii'ii'm'ittiiij 



mW. 



WW-'''- 






i 



: 



H 



flfff 

; 



;,; 



I 



; 



;i 



i 



■■1 



i 



I'm 




ss 



n^sa. 






5*/ 



■ tl li' rM iii ii> 



Mm.^ 



CQEMRIGHT DEPOSIT. 



/ 



THE BOOK OF ICE-CREAM 



Edited by L. H. BAILEY 

Carleton: The Small Grains. 

B. M. Duggar: The Physiology of Plant 
Production. 

J. F. Duggar: Southern Field Crops. 

Fisk: The Book op Ice-Cream. 

Gay: Breeds of Live-stock. 

Gay: Principles and Practice of Judging 
Live-Stock. 

Goff: Principles of Plant Culture. 

Guthrie: The Book of Butter. 

Harper: Animal Husbandry for Schools. 

Harris and Stev.art: The Principles of 
Agronomy. 

Hitchcock: Text-book of Grasses. 

Jeffery: Text-Book of Land Drainage, 

Jordan: Feeding of Animals, Revised, 

Livingston: Field Crop Production. 

Lyon: Soils and Fertilizers. 

Lyon, Fippin and Buckman: Soils; Their 
Properties and Management. 

Mann: Beginnings in Agriculture. 

Montgomery: The Corn Crops. 

Morgan: Field Crops for the Cotton-Belt. 

Mumford: The Breeding of Animals. 

Piper: Forage Plants and their Culture. 

Sampson: Effective Farming. 

Thorn and Fisk: The Book of Cheese. 

Warren: Elements of Agriculture. 

Warren: Farm Management. 

Wheeler: Manures and Fertilizers. 

White: Principles of Floriculture. 

Widtsoe: Principles of Irrigation Prac- 
tice. 



THE 
BOOK OF ICE-CREAM 



BY 

WALTER W. FISK 

w 

ASSISTANT PROFESSOR OF DAIRY INDUSTRY, NEW YORK 

STATE COLLEGE OF AGRICULTURE AT 

CORNELL UNIVERSITY 



N^m fork 
THE MACMILLAN COMPANY 

1919 

All rights reserved 






Copyright, 1919 

By the MACMILLAN COMPANY 

Set up and electrotyped. Published November, 1919. 



DEC il iyi9 



©a.A535996 



^^ . iK I 






PREFACE 

The older ones of us look back on the ice-cream of our 
youth as a luxury, to be expected on festivals and holi- 
days. The rising generation, however, is coming to look 
on it as a food. Once the manufacture of the confection- 
ery shop and the household, it is now produced in great 
quantities by concerns devoting themselves to it entirely, 
making it by highly developed standardized processes. 
A line of special machinery has been perfected for its 
manufacture. The subject is taught in the colleges. Yet 
the home manufacture has not passed and should not 
pass; rather should the product be made more frequently 
and in larger quantity in the household. 

No longer must one offer an excuse for a book on ice- 
cream. This book is made for class-room and laboratory 
use, growing out of the author's teaching experience; 
the manufacturer's interest has been set forth; yet it 
is hoped that the housewife will find directions for her 
use. 

Acknowledgment is due the following parties for 
valuable assistance either for the illustrations, or definite 
information or helpful criticisms: Henry Vogt Machine 
Co., Louisville, Ky.; Wheats Ice Cream Co., Buffalo, 
N. Y.; DeLaval Separator Co., New York, N. Y.; Jamison 
Cold Storage Door Co., Hagerstown, Md.; Merrell-Soule 
Co., Syracuse, N. Y.; The Ekenberg Co., Cortland, N. Y.; 
Chapin-Sacks Mfg. Co., Washington, D. C; The Cream- 
ery Package Mfg. Co., Chicago, 111.; York Mfg. Co., 
York, Pa.; Davis- Watkins Dairymen's Mfg. Co., Chicago. 



vi PREFACE 

111.; J. G. Cherry Co., Cedar Rapids, la.; Emery Thomp- 
son Machine and Supply Co., New York, N. Y.; T. D. 
Cutler, Ice-Cream Trade Journal, New York, N. Y.; 
Brunswick Refrigerating Co., New Brunswick, N. J.; 
L. O. Thayer, The International Confectioner, New York, 
N. Y.; Mojonnier Bros., Chicago, 111.; Sharpies Separator 
Co., West Chester, Pa.; Joseph Burnett Extract Co., 
Boston, Mass.; Nafis Glass Co., Chicago, 111.; J. E. Reyna, 
Dept. of Drawing, New York State College of Agri- 
culture, Ithaca, N. Y. The following members of the 
Dairy Dept. of the New York State College of Agriculture 
at Cornell University, Ithaca, N. Y: W. A. Stocking, 
H. E. Ross, T. J. Mclnerney, W. E. Ayres, G. C. Dutton, 
H. C. Troy, E. S. Guthrie, G. C. Supplee. 

W. W. FISK. 

Ithaca, N. Y., 
March 1, 1919. 



TABLE OF CONTENTS 

(Numbers in the text refer to paragraphs) 
CHAPTER I 

PAGES 
GENERAL STATEMENTS ON ICE-CREAM 1-7 

Materials used in ice-cream, 1; Definition of 
ice-cream, 2; Problems of ice-cream-making, 3; Ice- 
cream-making a science, 4. 

CHAPTER II 

MILK AND CREAM AS RELATED TO ICE-CREAM ......... 8-24 

Method of securing supply, 5; Quality of 
milk and cream desired, 6; Why milk and cream 
are not of the desired quality, 7; The flavor of 
foods eaten by the cow, 8; The absorption of 
flavors and odors in the atmosphere, 9; The 
unhealthy condition of the cow, 10; The bac- 
teria in the milk, 11; The sediment test, 12; How 
to prevent the growth of micro-organisms in the 
milk and cream, 13; Milk and cream production 
and handling, 14; Clarifier, 15; The chemical 
composition of the milk and cream, 16. 

CHAPTER III 

MANUFACTURED MILK PRODUCTS AS RELATED TO ICE- 
CREAM 25-42 

Condensed and Evaporated Milk: Method of 
manufacture, 17; Standards for condensed milk, 
18; Conditions essential for a milk condensory, 19; 
Supply of condensed milk for the ice-cream plant, 
20. Milk Powder: Standards for milk powder,' 21; 
Powdered milk processes, 22; Merrell-Soule 

vii 



viii TABLE OF CONTENTS 

PAGES 

powdered milk, 23; History of Merrell-Soule proc- 
ess, 24; Uses of Merrell-Soule powder in ice-cream, 
25; Ekenberg powdered milk, 26; Uses of Eken- 
berg powder in ice-cream, 27; Butter, 28. 

CHAPTER IV 

SUGAR, CHOCOLATE PRODUCTS, FRUITS, STABILIZERS 

AND FILLERS 43-56 

Sugar, 29; Invert sugar, 30; Sugar-saving sub- 
stitutes, 31; Cocoa and cocoa products, 32; Man- 
ufacture of chocolate and cocoa, 33; Composition 
of cocoa products, 34; Adulteration of cocoa 
and standards of purity, 35; Chocolate sirup, 36; 
Fruits, 37; Nuts, 38; Stabilizers and fillers, 39; 
Gelatine, 40; Preparing gelatine for use in the ice- 
cream, 41; Gum tragacanth, 42; Other substances 
used as binders, 43; Eggs, 44; Starchy fillers, 45; 
Prepared ice-cream powders, 46; Rennet, 47. 

CHAPTER V 

FLAVORING EXTRACTS 57-68 

Vanilla Extract: Nature of vanilla plant, 48; 
Curing vanilla beans, 49; Marketing vanilla beans, 
50; Production of vanilla beans, 51; The ingredi- 
ents of vanilla extract, 52; The chemistry of van- 
illa, 53; Adulteration of va.silla extract, 54. Lemon 
Extract: Preparation of lemon oil, 55; The chem- 
istry of lemon oil, 56; Orange extract, 57; Fruit 
extracts, 58. 

CHAPTER VI 

CLASSIFICATION 69-80 

Classification of ice-cream, 59; Receipts for ice- 
cream, 60; Vanilla ice-cream, 61; Chocolate ice- 
cream, 62; Caramel ice-cream, 63; Coffee ice-cream, 
64; Maple ice-cream, 65; Fruit ice-cream, 66; Nut 



TABLE OF CONTENTS ' ix 

PAGES 

ice-cream, 67; Bisque ice-cream, 68; Mousse, 69; 
Cooked ice-cream, 70; Parfait, 71; Puddings, 72; 
Custards, 73; Ices and sherbets, 74; Ices, 75; Water 
sherbets, 76; Punches, 77; Milk sherbets, 78; 
Lacto, 79. 

CHAPTER VII 

EQUIPMENT 81-100 

Freezers, 80; Mixers, 81; Gelatine kettles, 82; 
Hardening the ice-cream, 83; Packing-cans, 84; 
Ice crushers, 85; Ice-cream can washers, 86; Emul- 
sors, creamers, and homogenizers, 87; Cost of 
equipment, 88. 

CHAPTER VIII 

REFRIGERATION AS APPLIED TO ICE-CREAM-MAKING. . . 101-128 

Terms used, 89. Natural Ice: The ice field, 90; 
The ice-house, 91; Harvesting and storing, 92; 
Amount of ice needed, 93; Use of ice and salt 
mixture, 94. Mechanical Refrigeration: Principles 
of mechanical refrigeration, 95; Materials used 
in mechanical refrigerating systems, 96; Opera- 
tion of refrigerating machines, 97; The compres- 
sion system, 98; Parts of a compression system, 
99; Operation of direct expansion compression 
system, 100; Location of evaporating coils, 101; 
Notes on operating compression system, 102. 
Absorption Systems: Operation of absorption re- 
frigerating systems, 103; Arrangement of double 
pipe and atmospheric absorption machines, 104. 

CHAPTER IX 

PREPARING THE MIX 129-133 

Importance of preparing the mix, 105; Usual 
procedure in preparing the mix, 106; Temperature 
of the mix, 107. 



X TABLE OF CONTENTS 

CHAPTER X 

PAGES 
FREEZING PROCESS 134-144 

Purpose of freezing, 108; Rate of freezing, 109; 
Proper method of freezing, 110; Over-run or swell, 
111; Condition of ice-cream when removed from 
freezer, 112; Freezing sherbets and ices, 113. 

CHAPTER XI 

HARDENING ICE-CREAM 145-162 

Methods of hardening, 114; Hardening in ice and 
salt mixture, 115; The slush-box or brine-box 
method of hardening, 116; The hardening-room, 
117; The still-air type, 118; The gravity air-type, 
119; The forced-air type, 120; Defrosting the 
coils, 121; Time required for hardening, 122; Ef- 
fects of hardening on quality, 123; Fancy molded 
ice-cream, 124. 

CHAPTER XII 

JUDGING AND DEFECTS OF ICE-CREAM 163-169 

Score-cards, 125; Explanation of character- 
istics mentioned in score-card, 126; Defects in 
ice-cream, 127; Defects in flavor, 128; Defects in 
body and texture, 129; Defects in richness, 130; 
Defects in appearance, 131; Defects in package, 
132. 

CHAPTER XIII 

BACTERIA IN RELATION TO ICE-CREAM 170-182 

Sources of bacteria in ice-cream, 133; The ef- 
fect of freezing and hardening on the bacterial 
count, 134; Types of organisms in ice-cream, 135; 
The total-acid groups, 136; The inert group, 137; 
The alkaU group, 138; The peptonizing group, 139; 
Colon Bacilli in ice-cream, 140; Difficulties in 
studying the bacteriology of ice-cream, 141. 



TABLE OF CONTENTS sd 

CHAPTER XIV 

PAGES 

TESTING 183-245 

The Babcock Test: Testing whole milk for fat, 
142; Composite samples of milk, 143; Measuring 
the sample, 144; Adding the acid, 145; Whirling 
the sample, 146; Reading the test, 147; Appear- 
ance of a completed test, 148; Care of the test- 
bottles, 149; Testing cream, 150; Cream testing 
apparatus, 151; Sampling cream, 152; Making the 
cream test, 153; Tempering the fat and reading the 
percentage, 154; Testing skim-milk, 155; Modi- 
fications of the Babcock test for ice-cream, 156; 
The glacial acetic and hydrochloric acid test, 157; 
The sulfuric acid test, 158; Acetic and sulfuric 
acid test, 159; The lactometer, 160; Calculating 
the solids not fat in the milk, 161; Testing milk 
for acidity, 162; Test for formaldehyde, 163; Test 
for boiled milk, 164. Testing Butter for Fat, Mois- 
ture, and Salt: Preparing the sample, 165; Test- 
ing butter for fat, 166; Testing butter for mois- 
ture, 167; Testing butter for salt, 168; Test for 
viscosity, 169; Standardization, 170; Benkendorf 
test for over-run in ice-cream, 171 ; Test to deter- 
mine the hardness of ice-cream, 172. Mojonnier 
Tester: General preliminary information, 173; Test- 
ing evaporate, sweetened condensed, bulk con- 
densed milk, ice-cream (mix or melted) for fat 
or total solids, 174; Fat determination, 175; Total 
solids determination, 176; Testing butter, 177; 
Testing fresh milk, skim-milk, whey, and butter- 
milk for fat and total solids, 178; Testing powdered 
milk, cocoa, malted milk and milk chocolate for 
fat and total solids, 179; Testing cream for fat and 
total solids, 180; List of precautions to observe 
in operating Mojonnier tester, 181. Mojonnier 
Over-run Tester: Adjusting cups for mix, 182; 
Actual operation, 183; Controlling the over-run, 
184; Savings and economics, 185. 



xii TABLE OF CONTENTS 

CHAPTER XV 

PAGES 
MARKETING AND BUSINESS MANAGEMENT 246-271 

Demand for ice-cream, 186; Food value of ice- 
cream, 187; Locating a market, 188; Method of 
delivery, 189; Cost of delivery, 190; Packages 
used for delivery, 191; Advertising, 192; Sales- 
men, 193. Business Management: Purchase of 
raw material, 194; Price of dairy products, 195; 
Bookkeeping system, 196; Shipping clerk, 197; 
Report blanks, 198; Losses, 199; Pack-cans and 
tubs, 200; Rusty pack-cans, 201; Soft ice-cream, 
202; Transferring, 203. Laws: Sanitary condi- 
tions and adulterated milk and cream, 204; Bab- 
cock test, 205; Purchaser's or vender's license, 206; 
Legal standards, 207. 

CHAPTER XVI 

CONSTRUCTION AND ARRANGEMENT OF THE FACTORY . . . 272-286 

Location of the plant, 208; Arrangement of 
machinery, 209; Loading platform, 210; Light, 
211; Ventilation, 212; Floors, 213; Ceilings and 
side-walls, 214; Sinks and cupboards, 215; Locker 
rooms, 216; Cleanliness, 217; Cleaning utensils, 
218; Cleaning the floor, 219; Store-room and 
work shop, 220; Sanitary codes, 221. 

CHAPTER XVII 

HISTORY AND EXTENT OF THE INDUSTRY . 287-296 

Early history, 222; Development of ice-cream 
in the household, 223; Development of wholesale 
ice-cream, 224; Extent of the industry, 225. 



LIST OF ILLUSTRATIONS 

PAGE 

Fig. 1. — Refrigerator room for storing cream and milk in 
a large ice-cream plant. (Courtesy of Wheat's Ice 
Cream Co., Buffalo, N. Y.) 12 

Fig. 2. — Filters from sediment tests showing the amount 
of dirt in different samples of milk. These are the 
grades made by the New York City Board of Health . . 18 

Fig. 3. — Sharpies milk clarifier 22 

Fig. 4. — De Laval milk clarifier, turbine drive 22 

Fig. 5. — ^View of modern condensory showing hot wells, 
vacuum pan, vacuum pump and cooling tanks. (Cour- 
tesy of Wheat's Ice Cream Co., Buffalo, N. Y.). . . . . 26 
Fig. 6. — Fruit storage in large ice-cream plant. (Courtesy 

of Wheat's Ice Cream Co., Buffalo, N.-Y.) 51 

Fig. 7. — Steam jacketed kettle for heating gelatine 53 

Fig. 8. — Hand freezer with tub and can cut away showing 

ice and salt mixture and beaters and scrapers in the can. 82 

Fig. 9. — Hand freezer with fly wheel, using salt and ice 
mixture for freezing. The capacity of this freezer is 
five gallons 82 

Fig. 10. — Power driven tub and can freezer using a salt 
and ice mixture. The can, dasher and gears are shown 
removed 82 

Fig. 11. — Horizontal brine freezer attached to a salt and 
ice brine box. The pump is behind the box 83 

Fig. 12. — ^Verticle belt driven brine freezer connected to 
ice and salt brine box. (Courtesy of Emery Thompson 
Machine and Supply Co., New York City.) 84 

Fig. 13. — Perfection brine freezer, direct motor drive. 

(Courtesy of J. G. Cherry Co., Cedar Rapids, Iowa.) . . 85 

xiii 



xiv LIST OF ILLUSTRATIONS 

PAGE 

Fig. 14. — Progress vertical belt drive brine freezer. (Cour- 
tesy of Davis Watkins Dairymen's Manufacturing Co., 
Chicago, 111.) 86 

Fig. 15. — Emery Thompson vertical direct motor drive 
brine freezer. (Courtesy of Emery Thompson Machine 
and Supply Co., New York City.) 87 

Fig. 16. — Fort Atkinson belt drive brine freezer. (Cour- 
tesy of Creamery Package Manufacturing Co., New 
York City.) 88 

Fig. 17. — Disc brine freezer either continuous or batch. 
(Courtesy of Creamery Package Manufacturing Co., 
New York City.) 89 

Fig. 18. — Side view of disc freezer shown in Fig. 17, show- 
ing brine tank and pump. (Courtesy of Creamery 
Package Manufacturing Company, New York City.) 89 

Fig. 19. — Freezing discs of freezer shown in Figs. 17 and 18. 
The scrapers for removing the frozen ice-cream from 
the discs and the screw to force it out of the delivery 
spout are shown. (Courtesy of Creamery Package 
Manufacturing Co., New York City.) 90 

Fig. 20.— a pasteurizer or ripener used as an ice-cream 
mixer. Strips are attached to the coils to prevent the 
settling of the sugar on the bottom 90 

Fig. 21. — Minnetonna starter can or ice-cream mixer. 
(Courtesy of Davis-Watkins Dairymen's Manufactur- 
ing Co., Chicago, 111.) 91 

Fig. 22. — ^Alaska ice-cream mixer. The side is cut away 
showing the coils and insulation. The mechanical agi- 
tator is seen at the bottom. The cover fits air tight so 
that by means of an air pump and air pressure the mix 
may be forced to the freezer. (Courtesy of Creamery 
Package Manufacturing Co., New York City.) 92 

Fig. 23. — ^Wizard ice-cream mixer. (Courtesy of Cream- 
ery Package Manufacturing Co., New York City.) . . 92 

Fig. 24. — Emery Thompson ice-cream mixer. (Courtesy 
of Emery Thompson Machine and Supply Co., New 
York City 92 



LIST OF ILLUSTRATIONS xv 

PAGE 

Fig. 25. — Two types of ice-cream packing-cans 93 

Fig. 26.— Ice spud 94 

Fig. 27. — Ice cracker 94 

Fig. 28. — Perforated ice shovel 94 

Fig. 29. — Ice crusher with tight and loose pulley for me- 
chanical power. The teeth or picks on the drum may 
be seen. 94 

Fig. 30. — The perfection ice cream can washer and ster- 
ilizer. (Courtesy of J. G. Cherry Co., Cedar Rapids, 
Iowa.) 94 

Fig. 31. — Fort Atkinson ice-cream can washer and steril- 
izer. (Courtesy of Creamery Package Manufacturing 
Co., New York City.) 95 

Fig. 32. — De Laval centrifugal emulsor. (Courtesy of 

De Laval Separator Co., New York City.) 95 

Fig. 33. — Perfection cream maker and emulsifier. (Cour- 
tesy of J. G. Cherry Co., Cedar Rapids, Iowa.) 96 

Fig. 34. — Progress homogenizer. (Courtesy of Davis- 
Watkins Dairymen's Manufacturing Co., Jersey City, 
N. J.) 97 

Fig. 35. — Gaulin homogenizer. (Courtesy of Creamery 

Package Manufacturing Co., New York City.) 98 

Fig. 36.^ — ^Sharples centrifugal emulsor. (Courtesy of 

Sharpies Separator Co. (West Chester, Pa.) 99 

Fig. 37.— Hand ice-saw 106 

Fig. 38. — Ice-plow with marker 106 

Fig. 39.— Splitting fork 107 

Fig. 40. — ^Approximate temperatures obtained with dif- 
ferent proportions of ice and salt 108 

Fig. 41. — Refrigeration available with different percent- 
ages of salt 109 

Fig. 42. — Diagram showing relation of heat to tempera- 
ture 113 

Fig. 43. — Simplest compression system of refrigeration. . 116 



xvi LIST OF ILLUSTRATIONS 

PAGE 

Fig. 44. — Compression system of refrigeration in which the 
flow of liquid is regulated by expansion valve and the 
liquid changes to a gas in the coil of pipe thereby cool- 
ing the brine. The gas then passes off into the at- 
mosphere 117 

Fig. 45. — Complete system of direct expansion refriger- 
ating system 118 

Fig. 46. — Combination of direct expansion and brine stor- 
age tanks. This is the same system as shown in Fig. 45 
with the brine tank (T) added in the refrigerator 120 

Fig. 47. — Arrangement where it is desired to use cold brine 
for cooling in some machine such as an ice-cream freezer. 
This is the same refrigerating system as shown in Figs. 
45 and 46 121 

Fig. 48. — Diagram of the Vogt absorption refrigerating 
machine, showing pipe connections and directions in 
which the liquids and gases travel throughout the en- 
tire system. (Courtesy of Henry Vogt Machine Co., 
Louisville, Kentucky.) 123 

Fig. 49. — General arrangement of double pipe absorption 
refrigerating machine, showing the connections and the 
direction in which the liquids and gases flow. (Cour- 
tesy of York Manufacturing Company, York, Pa.) . . 124 

Fig. 50. — General arrangement of atmosphere absorption 
. machine showing the connections and the direction in 
which the liquids and gases flow. (Courtesy of York 
Manufacturing Company, York, Pa.) 126 

Fig. 51. — Mixing room in large ice-cream plant. (Courtesy 

of Wheat's Ice Cream Company, Buffalo, N. Y.) .... 132 

Fig. 52. — Battery of freezers in a large ice-cream plant. 
(Courtesy of Chapin-Sacks Manufacturing Co., Wash- 
ington, D. C.) 135 

Fig. 53. — Different styles of transfer ladles or scoops 146 

Fig. 54. — Plank box for hardening ice-cream in a salt and 
ice mixture. The cans are placed in perforated cylin- 
ders so that the cans may be changed and the ice will 
not fall in and fill the space 147 



LIST OF ILLUSTRATIONS xvii 

PAGE 

Fig. 55. — Still-air hardening-room showing evaporating 
coils forming shelves on which the pack-cans of ice- 
cream are placed to harden. Other evaporating coils 
may be seen on the sides and ceiling. (Courtesy of 
Brunswick Refrigerating Co., New Brunswick, N. J.) 150 

Fig. 56. — Forced air hardening-room. (Courtesy of Chapin- 
Sacks Manufacturing Co., Washington, D. C.) 152 

Fig. 57. — Brick ice-cream trowels. Straight and bent 

handles 158 

Fig. 58. — Quart and sectional brick molds. The sec- 
tional bricks hold several quarts 159 

Fig. 59. — Brick hardening-room. (Courtesy of Chapin- 

Sacks Manufacturing Co., Washington, D. C. 160 

Fig. 60. — Center mold and examples 161 

Fig. 61. — Individual ice-cream molds and ice cave for pack- 
ing molds 161 

Fig. 62. — ^Babcock milk pipette 185 

Fig. 63. — Babcock whole milk test-bottle 186 

Fig. 64.— Acid measure for Babcock test 187 

Fig. 65. — Diagram showing the motion and position of a 

test-bottle while mixing the milk and the acid 188 

Fig. 66. — Hand and power centrifuges 189 

Fig. 67. — Proper way to read the percentage of fat in a Bab- 
cock whole milk test-bottle 191 

Fig. 68" — Babcock cream test-bottles 193 

Fig. 69. — Method of reading the percentage of fat in a Bab- 
cock cream test-bottle 195 

Fig. 70.— Skimmed-milk test-bottle 196 

Fig. 71. — Quevenne lactometer 199 

Fig. 72.— Board of Health lactometer. . . .* 200 

Fig. 73.— Nafis acid test 201 

Fig. 74. — Apparatus for testing ice-cream over-run by the 

Benkendorf method ; 213 

Fig. 75. — Mojoimier tester for fat and total solids. 217 



xviii LIST OF ILLUSTRATIONS 

PAGE 

Fig. 76. — Mojonnier over-run tester 241 

Fig. 77. — Ice-cream packing tubs 252 

Fig. 78. — ^Auto delivery truck for ice-cream 253 

Fig. 79. — Ice-cream cabinet with side cut away showing 
insulation and perforated cylinders on which the pack- 
cans of ice-cream set 254 

Fig. 80. — Different styles of ice-cream dishes 255 

Fig. 81. — Shipping platform and office of shipping clerk 
in a large ice-cream plant. (Courtesy of Wheat's Ice 

Cream Co., Buffalo, N. Y.) 261 

Fig. 82. — Revolving door used for putting the ice-cream 

into the hardening-room 263 

Fig. 83. — Plan of a small ice-cream plant 273 

Fig. 84. — Basement plan of large ice-cream plant 274 

Fig. 85. — First floor plan of plant shown in Fig. 84 275 

Fig. 86. — Second floor plan of plant shown in Figs. 84 

and 85 275 

Fig. 87. — A loading platform in a large ice-cream plant. 
(Courtesy of Chapin-Sacks Manufacturing Co., Wash- 
ington, D. C.) 276 

Fig. 88. — The value of skyhghts is shown by the well- 
lighted freezing-room, considerable floor space above 
being sacrificed for this purpose. (Courtesy of Wheat's 
Ice Cream Co., Buffalo, N. Y.) 277 



THE BOOK OF ICE-CREAM 



THE BOOK OF ICECREAM 

CHAPTER I 
GENERAL STATEMENTS ON ICE-CREAM 

Ice-cream is known commonly to-day as ja food, al- 
though in the past it was considered and used only as a 
delicacy or dessert. Because of the rapid growth of the 
industry and the large number and varying amounts of 
materials that can be used in the making of ice-cream, 
its composition may be varied within wide limits. The 
Federal Government and most of the States have set 
standards for ice-cream. Some products, such as cus- 
tards, sherbets, ices and the like, are usually included 
in the general discussion of ice-creams but technically 
should not be classed with them. 

1. Materials used in ice-cream. — The basis of ice-cream 
is some dairy product or a combination of dairy products, 
such as milk, cream, skim-milk, condensed milk, milk 
powder, homogenized or emulsified milk or cream, and 
the like. These materials contain varying amounts of 
fat and solids not fat, ranging from to several per cent. 
Either one or all may be used, as the manufacturer de- 
termines, to give the ice-cream the desired amount of fat 
and milk solids. The price often determines the kind and 
amounts of the different materials to be used. It is im- 
portant that these dairy products be clean; otherwise the 
ice-cream may have an undesirable flavor. 

1 



2 THE BOOK OF ICE-CREAM 

Sugar in some form must be used to sweeten ice-cream. 
Granulated sugar was employed ordinarily before the 
war. However, in conserving for the war, it was found 
that various sirups could be substituted. Corn sirup was 
commonly used, and some invert sugar, maple sirup and 
honey in smaller amounts. 

A large variety of materials may be utilized to flavor 
the ice-cream. The extracts commonly employed are 
vanilla and lemon. Fruits, either fresh, canned, pre- 
served, dried or candied, may be used as flavoring, various 
bread or cake products, such as macaroons, sweetened 
wafers and sponge cake, and also caramel and chocolate 
products, usually chocolate or cocoa. 

A little color of the proper shade to give the product 
the characteristic tint suggested by the flavor is com- 
monly added. 

If the ice-cream is not consumed as soon as it is made, 
ice crystals soon separate, causing it to become grainy 
in texture. In order to prevent this, some form of 
*' stabilizer" is added, commonly gelatine. However, 
gum tragacanth or some of the prepared ice-cream pow- 
ders may be used. 

2. Definition of ice-cream. — ^Because of the large vari- 
ation of materials, both in quantity and kind, that may 
be used in its making, the definitions of ice-cream are 
more or less elastic. The various dictionaries give the 
following definitions: Webster, — "Ice-cream is milk or 
cream sweetened, flavored, and congealed by a freezing 
mixture, sometimes instead of cream the materials of a 
custard are used"; Century, — "Ice-cream is a confection 
made by congealing variously flavored cream or custard 
in a vessel surrounded with a freezing mixture;" Stand- 
ard, — "Ice-cream is cream, milk or custard sweetened 



GENERAL STATEMENTS ON ICE-CREAM 3 

and flavored and frozen by a freezing mixture, being 
usually agitated by a dasher in the process to make it of 
uniform consistency/' The United States Department 
of Agriculture bases its definition * on the composition 
of the finished ice-cream. Its definitions are as follows: 

Ice-cream is a frozen product made from cream and 
sugar with or without a natural flavoring and contains 
not less than 14 per cent of milk-fat. 

Fruit ice-cream * is a frozen product made from cream, 
sugar and sound, clean, mature fruits, and contains not 
less than 12 per cent of milk-fat. 

Nut ice-cream * is a frozen product made from cream, 
sugar and sound non-rancid nuts and contains not less 
than 12 per cent of milk-fat. 

The National Association of Ice-Cream Manufacturers 
defines ice-cream and the adulterated product as follows: 
That for the purpose of this act ice-cream is hereby 
defined and standardized: 

First: Ice-cream is a frozen compound, varied a^ to 
kind and proportion of ingredients within the limits 
established by custom and usage. 
Second: Ice-cream consists chiefly of a sweetened and 
flavored mixture of cream, or cream and milk, or 
milk, with or without added milk-fat in the form of 
sound sweet butter or as contained in condensed, 
evaporated or concentrated milk or in milk powder, 
and with or without added milk solids not fat in the 
form of skim-milk powder or as contained in milk 
powder or in condensed, evaporated or concentrated 
skim-milk, or of a sweetened and flavored homogen- 
ized or emulsified mixture of sound, sweet butter, 
milk powder or skim-milk powder and water, with 
* Office of the Secretary, U. S. Dept. Agr., Bui. 19, 1906. 



THE BOOK OF ICE-CREAM 

the addition of gelatine, vegetable gum, or other 
wholesome stabilizer. 

Third: Standard ice-cream contains not less than 
eight (8) per cent milk-fat and the content of milk- 
fat and milk solids not fat combined shall not be 
less than eighteen (18) per cent except when the 
ingredients of standard ice-cream include eggs, fruit 
or fruit juice, cocoa or chocolate, cake, confections 
or nuts, such reduction of the percentage of milk-fat 
and milk solids not fat as may be due to the addition 
of such ingredients shall be allowed. 

Fourth: When ice-cream is sold or offered for sale 
without designation of its kind, quality or grade on 
a label, brand, or tag attached to the package or 
container, or, in case of removal from the original 
package or container, by a notice conspicuously 
posted in or at the place where such ice-cream is sold 
or offered for sale, it shall be deemed that such ice- 
cream is sold or offered for sale as of the grade of and 
for standard ice-cream, or better. That for the 
purposes of this act ice-cream shall be deemed to be 
adulterated : 

(1) If in quahty or grade it is lower than the pro- 
fessed standard of quahty or grade which it is sold 
or offered for sale. 

(2) If it contains any added poisonous or other 
added deleterious ingredient which may render 
such ice-cream injurious to health. 

(3) If it contains any rancid or renovated or process 
butter, or any fat or oil other than milk-fat and 
the fat or oil of contained eggs or nuts and the fat 
or oil of substances used for flavoring purposes 
only. 



GENERAL STATEMENTS ON ICE-CREAM 5 

(4) If it consists in whole or in part of any filthy or 
decomposed substance which may render such 
ice-cream injurious to health, or is otherwise so 
contaminated that such ice-cream is injurious to 
health. 
That for the purpose of this act ice-cream shall be 
deemed to be misbranded: 

First: If the label, brand, tag or notice under which 
it is sold or offered for sale is false or misleading in 
any particular as to the kind, grade or quality or 
composition of such ice-cream; or if any notice to 
the purchaser required by this act to be given is 
omitted. 
Second: If it is sold or offered for sale as the product 
of one manufacturer when in reality it is the product 
of another manufacturer: or if on the label, brand, 
tag or notice under which it is sold or offered for 
sale there is any false statement concerning the 
sanitary conditions under which such ice-cream is 
manufactured. 
So far the description of ice-cream has mentioned only 
the materials to be used and in some cases the chemical 
composition in so far as percentage of fat is concerned. 
It is evident that there is considerable difference of opin- 
ion regarding the minimum percentage of fat that the 
ice-cream should contain. It would seem that it might 
not only be desirable to mention the materials which 
could be employed, but also the percentage of fat and 
total solids or milk solids not fat, by means of a sliding 
scale. In the description, no account is taken of the 
bacterial-content of the ice-cream. The number of or- 
ganisms may or may not give an indication of the quality 
of the materials used and the sanitary condition under 



6 THE BOOK OF ICE-CREAM 

which the manufacturing and handling is done. When 
a bacterial standard for milk is universally recognized 
and enforced, then a bacterial standard for ice-cream 
may be enforced. It is to be desired that an adequate 
definition of ice-cream will be forthcoming and that this 
definition will be enforced. This will do much to im- 
prove the quality of the product. 

3. Problems of ice-cream-making. — The successful 
making of ice-cream calls for an understanding of the com- 
plex factors involved. These factors are: The production 
and handling of the milk and the milk products employed; 
the chemical and bacteriological composition of the milk 
products; the various tests used, such as fat, acid, tests 
for swell and the like; the blending of the flavors of the 
various products to secure the characteristic flavor de- 
sired; the freezing process and subsequent handling of 
the ice-cream; the construction and operation of the 
machinery. A working knowledge of the combination of 
the above factors is necessary to make ice-cream of uni- 
form quality. After the manufacture, the marketing of 
the product is a vital question and it should receive con- 
stant attention and study. 

4. Ice-cream-making a science. — Only recently has the 
making of ice-cream been recognized as founded on science. 
This is probably because in the past most of the ice-cream 
was made in small amounts largely in the household, while 
now it is manufactured in large quantities in commercial 
plants. 

In these large plants and in the agricultural colleges, 
considerable attention has been paid recently to the 
making of ice-cream. No description of the process can 
replace experience. Description of appearance of the 
ice-cream and conditions during the making process, in 



GENERAL STATEMENTS ON ICE-CREAM 7 

terms definite and clear enough to be readily understood 
by beginners, has been found to be impossible. Certain 
principles and essentials of practice can be presented, 
which form the foundation for intelligent work. The 
more study given to the process, and the better the under- 
lying principles are understood, the further we will depart 
from rule-of-thumb practice. 



CHAPTER II 

MILK AND CREAM AS RELATED TO ICE- 
CREAM 

Several milk products are commonly used in ice- 
cream, namely: whole and skimmed-milk, cream, con- 
densed milk, evaporated milk, milk powder and butter. 
These may be utilized singly or in combinations. The 
most important characteristic of the milk products is 
their flavor which should be clean and sweet; if not, it is 
likely to impart its undesirable flavor to the ice-cream. 
Much might be written on the production, care and 
composition of the milk and cream. Space will not per- 
mit this, but the essential factors as related to ice-cream 
will be discussed. 

5. Method of securing supply. — The ice-cream indus- 
try offers an entirely different problem from the other 
branches of the dairy industry in relation to securing a 
supply of milk and cream. This is due to the location. 
There are usually brokers or commission men who are 
willing to handle butter, cheese, condensed milk and 
other dairy products which are not comparatively as 
perishable as ice-cream. Therefore, the butter, cheese, 
and condensed milk plants are located where they can 
secure easily a supply of raw milk, which is in the coun- 
try. On the other hand, there are no brokers or com- 
mission men who handle ice-cream; therefore, the ice- 
cream is sold directly to the retailer or consumer. Because 
of the ease of delivery, the ice-cream plant is located in 

8 



MILK AND CREAM 9 

the center of population, namely, the city or village. It 
has not proved satisfactory, either from the view point 
of quality or cost of production, to make the ice-cream 
near the supply in the country and ship the finished 
product to the city. 

Due to the location of the ice-cream plant in the city, 
there are four ways of securing the raw materials: 

1. Buy milk and cream from dealer. 

2. Operate creamery in country and get supply from it. 

3. Use surplus from other dairy operations, and pur- 

chase necessary balance. 

4. Use of homogenized or emulsified milk and cream. 

Each ice-cream concern will have to decide, after care- 
fully considering all the factors, which method is best 
adapted for its use. Each has its advantages and dis- 
advantages. 

Buying milk and cream from dealer. 
Advantages: 

1. No surplus to dispose of. 

2. Minimizes labor in the ice-cream plant. 

3. Requires less capital. 
Disadvantages : 

1. Uncertainty of cream supply. 

2. No control of quality. 

3. Higher cost of cream. 

4. No control of fat-content of cream. 

5. Must have separate supply of condensed milk. 

6. At mercy of cream dealer. 

7. Difficult to dispose of any surplus. 
Operating creamery in country and getting supply from it. 

Advantages: 

1. Certain of known supply. 



10 THE BOOK OF ICE-CREAM 

2. Better control of quality. 

3. Easy to dispose of any surplus. 

4. Usually a cheaper supply. 

5. Can secure cream of desired fat-content. 

6. Can pay patrons better price for milk. 

7. May make own supply of condensed milk. 

8. More independent. 
Disadvantages: 

1. Requires more capital. 

2. Requires more labor. 

3. Requires more management. 

4. Must deal directly with the dairy-men. 

5. Transportation. 

6. Must find suitable location. 

Using surplus from other dairy operations and purchasing 
necessary balance. 
Advantages : 

1. Makes an outlet for surplus. 

2. Economy of delivery. 
Disadvantages : 

1. May make too large a business. 

2. May not have necessary equipment, especially 

refrigerator. 

3. May not be able to purchase necessary 

balance of supply. Disadvantages same as 
buying from dealer. 

4. If side line, may not give it proper attention. 

5. May not have surplus only part of year so 

balance of year do not care to operate. 
Use of homogenized or emulsified milk and cream. 
Advantages: 

1. When big demand can quickly make supply 
of cream. 



MILK AND CREAM U 

2. Sweet cream can be secured in localities where 

it can not be produced easily, especially the 
South. 

3. Does not necessitate carrying a large surplus 

of cream. 

4. Usually a cheap supply of cream. 
Disadvantages : 

1. Tendency to try to use butter and milk prod- 

ucts of inferior quality. 

2. Because of the physical nature of homogenized 

cream, try to use less fat in it. 

6. Quality of milk and cream desired. — Regardless of 
how obtained, the cream and milk should be of the de- 
sired quality for ice-cream manufacture. The cream 
should be clean flavored and sweet. In some plants, 
when the cream is slightly sour, a neutralizer is added, 
but this practice should not be followed. Better care, 
better holding methods or both should be employed to 
insure sweet cream. The refrigerated room in which 
milk and cream are stored in a large ice-cream plant is 
shown in Fig. 1. Cream for ice-cream-making should 
not have more than 0.24 per cent of acid by the acid test. 
(For use of acid test, see Chapter XIV.) In order to in- 
sure sweetness, cream is usually pasteurized. Pasteuriza- 
tion * is heating to a temperature suflftciently high, usually 
145° F. and held at this temperature for a sufficient 
period, usually thirty minutes, to kill most of the organ- 
isms in the milk and then rapidly cooling to 50° F. or 
below. When pasteurized cream and milk are used, there 
is not the danger from disease organisms that there is 

* Ayres, S. H., " The Present Status of the Pasteurization of 
Milk/' U. S. Dept. Agr. Bui. 342, 1916. 



12 



THE BOOK OF ICE-CREAM 



from raw cream. An ''aged" cream is to be desired for 
ice-cream-making because it is more viscous. By ''aged" 
is meant the holding of the cream for a period after sepa- 
rating before it is made into ice-cream. Usually it is 
aged for twenty-four to thirty-six hours. While aging it 
must be kept cold so it will not sour and it should not be 




Fig. 1.— Refrigerated room for storing milk and cream in a large 

ice-cream plant. 



frozen. It is hard to melt frozen cream and it is liable to 
cause the ice-cream to be grainy. 

The demand for ice-cream fluctuates with the weather 
changes. When it is hot there is an extensive demand but 
if the weather rapidly becomes cool this demand suddenly 
decreases or vice versa. This means that the ice-cream- 
rriaker either must carry or have at his disposal a variable 
supply of cream. When hot weather increases the de- 



MILK AND CREAM 13 

mand, there may not be time to age the cream or it may 
be held so long that it becomes sour. Homogenized or 
emulsified cream is to be desired for ice-cream-making 
because it gives a smoother body and texture to the 
product. This is undoubtedly due to the fat globules and 
other solids being broken up into smaller particles by the 
process. 

7. Why milk and cteam are not of the desired quality. — 
Some milk and cream has undesirable flavors which may 
be more or less pronounced. These are due to: the flavor 
of foods eaten by the cow; the absorption of flavors and 
odors from the atmosphere; the health of the cow; the 
bacteria present. If not properly handled, the milk and 
cream will soon become sour. 

8. The flavor of foods eaten by the cow. — The presence 
of undesirable flavors in the milk is due many times to 
the cows eating foods with very pronounced flavors. 
Most common of these foods are onion, garlic, turnips, 
cabbage, decayed ensilage, various pasture weeds, and 
the like. The flavoring oils are volatile and so are able 
to pass easily through all the tissues of the animal, and 
in a short time pass off through the various excretory 
channels. During the time that the food is undergoing 
digestion, these volatile oils are not only present in the 
milk, but all the tissues of the animal. By the time the 
process of digestion is completed, the volatile flavors will 
have passed away largely. Therefore, if the time of 
milking and feeding are properly regulated, a dairy-man 
may feed considerable quantities of strong-flavored food, 
without any appreciable effect on the flavor of the milk. 
To do this successfully, the cows should be fed immedi- 
ately before or after milking, preferably the latter. This 
allows time for the digestive process to take place, during 



14 THE BOOK OF ICE-CREAM 

which time the volatile substances will have passed away. 
While, if the milking occurred three or four hours after 
feeding, these volatile substances would be present in the 
milk and so flavor it. 

In the case of those plants which grow wild in the 
pasture and to which the cows have continued access, it 
is much more difficult to overcome the bad flavor in 
the milk. The only thing which can be done is to allow 
the cows to pasture for a short time immediately 
after milking. This will make it necessary to supple- 
ment the food of the pasture with dry feed, or to have 
another pasture where these undesirable plants do not 
grow. 

9. The absorption of fiavors and odors in the atmos- 
phere. — Milk, especially when warm, possesses a remark- 
able ability to absorb and retain odors in the surrounding 
atmosphere. For this reason, the milk should be exposed 
only in a surrounding of clean pure air. Some of the 
common sources of these undesirable odors are : bad smell- 
ing stables; unclean cows; aerating milk near hog pens, 
barnyards, swill barrels, and like odoriferous sources; 
strong-smelling feeds in the stable during milking, and 
the like. The only way to overcome these undesirable 
flavors and odors in the milk is not to expose the milk to 
them. The safest policy is to remove the source of the 
odor. 

10. The unhealthy condition of the cow. — Milk secreted 
just before or just after parturition is different in physi- 
cal properties and chemical composition from that se- 
creted at any other time during the lactation period. 
This milk is known as colostrum. It is considered unfit 
for human lood, either as milk or products manufactured 
from the milk. Most states consider colostrum adulter- 



MILK AND CREAM 15 

ated milk, and prohibit its sale fifteen days before or 
five days after parturition.* 

Whenever disease manifests itself in the cow, the milk 
should be discarded at once as human food. Some dis- 
eases are common both to the cow and man, such as 
tuberculosis and foot-and-mouth disease. If such dis- 
eases are present in the cow, the milk acts as a carrier for 
them to man. Digestive disorders of any sort in the cow 
are frequently accompanied by undesirable flavors in the 
milk. These are not believed to be due to the food eaten, 
but to the bad condition of the animal. On resuming a. 
normal condition, these undesirable flavors disappear. 
This is especially noticeable when cows are turned out 
to pasture for the first time in the spring, or when they 
are pastured on rank fall feed, such as second-growth 
clover. 

11. The bacteria in the milk. — The bacteria are 
microscopic unicellular plants without chlorophyll. Be- 
sides bacteria, there are other forms of the lowest orders 
of the vegetable kingdom found in milk, such as yeasts 
and molds. The general characteristics of yeast and 
bacteria are somewhat similar. Bacteria are very widely 
distributed throughout nature. They are so small that 
they may float easily in the air or on particles of dust. 
They are so resistant to adverse conditions of growth 
that they may be present in a dormant or spore stage, 
and thereby not be recognized readily; when suitable 
environments for growth are again produced, germina- 
tion takes place at once. They are found in all surface 
water, on the surface of the earth, and upon all organic 

* N. J. Agricultural Law, 1913, section 30; Mich. Agricultural 
Law, 1915, section 77; Wis. Agricultural Law, 1913, section 4601- 
49-5. 



16 THE BOOK OF ICE-CREAM 

matter. There are a great many different groups of 
bacteria, some beneficial and some harmful to man. As 
they are so small, it is difficult to differentiate between 
the beneficial and harmful groups, except by the results 
produced or by a careful study in an especially equipped 
laboratory. Bacteria have many forms, the three com- 
mon forms being : spherical (coccus) ; rod-like or cylindri- 
cal (bacillus); and corkscrew (spirillum). The bacteria 
reproduce very rapidly by fission, that is, a transverse 
partition forms in the cell and when this partition is 
completed, the cell is divided. There are then two bac- 
teria where there was but one before. In some cases, this 
division has taken place regularly in twenty to thirty 
minutes. Like other plants, they are very sensitive to 
a food supply, to temperature, and to moisture, as con- 
ditions of growth. Inasmuch as the bacteria are plant 
cells, they must imbibe their food from materials in solu- 
tion. They may live on solid substances, but the food 
elements must be rendered soluble before they can be 
utilized. Bacteria prefer a neutral or slightly acid medium 
for growth, rather than an alkaline reaction; however, 
there are, many exceptions to this. The food for bacteria 
must contain carbon, hydrogen, oxygen, and nitrogen, 
together with small amounts of mineral matters. Or- 
ganic compounds make available food supplies. Ordinary 
milk furnishes a very favorable medium for the growth 
of bacteria because it contains an adequate and easily 
available food supply. In milk, there are certain groups 
of bacteria, which are ordinarily present, but any others 
which happen to get into the milk will live and rapidly 
multiply. Most forms of bacteria are dependent on tem- 
perature as a condition of growth. There is a range of 
temperature, more or less wide, at which the bacteria 



MILK AND CREAM 17 

will grow and multiply with the greatest rapidity. This 
is called the optimum temperature and varies with the 
different groups of bacteria, but for most it is between 
75° F. and 95° F. Growth of most of the bacteria found 
in milk will take place between 40° F.-45° F. to 105° F.- 
115° F. Above and below these temperatures growth 
is retarded, and, if carried to extremes, life will be de- 
stroyed. Like plants which form structures called seeds 
to carry them through conditions unfavorable to growth, 
so some groups of bacteria form spores. The spores are 
exceedingly resistant to unfavorable conditions of growth, 
such as heat, cold, drying, food supply, and even chemical 
agents. It is this property which makes it difficult to 
destroy some bacteria. 

Because of the harmful effect of the micro-organisms 
in the milk and cream, precautions should be taken to 
keep them out. If they do enter, their growth can be 
checked by keeping the milk and cream cold. What has 
been said regarding bacteria is true of molds and yeasts. 

12. The sediment test. — The amount of solid material 
or dirt in the milk is an indication of the amount of bac- 
terial contamination. It should be remembered that the 
strainer will take out the solid material, but the soluble 
portion and the bacteria will be left in the milk or cream. 
Thus an efficient strainer will defeat the sediment test. 
There are several sediment tests on the market. The 
test consists of filtering about a pint of milk through a 
cotton disc filter about an inch in diameter. The solid 
material or dirt is left on the filter. (Fig. 2.) The amount 
of dirt would indicate the amount of contamination in 
the milk. Much improvement in the quality of the milk 
has been accomplished by the use of the sediment test, 
because the cotton discs with the dirt are posted where 



18 THE BOOK OF ICE-CREAM 

each patron can see them and pride causes the careless 
dairy-man to take more pains in the care and handhng 
of his milk. 

13. How to prevent the growth of micro-organisms in 
the milk and cream. — Next in importance to clean pro- 
duction in the care of milk and cream, is the prevention 
of growth or development of the organisms in it. This 
is accomplished by cooling and keeping the milk and 



Fig. 2. — Filters from sediment tests showing the amount of dirt 
in different samples of milk. These are the grades made by the 
New York City Board of Health. 

cream cold and covered. If they are produced clean and 
kept covered, there are certain to be some micro-organisms 
in the milk and unless cooled these will develop and 
quickly spoil the milk and cream. Ross * and Mclnerney 
give the following summary regarding the cooling of 
milk and cream: 

''Milk becomes cool, of course, when it gives up its 
heat to some substance colder than itself, and in order to 
have a rapid exchange of temperatures between two 
substances it is necessary that they have approximately 
the same density. On account of the great difference in 
density between air and milk, the latter will cool very 

*Ross, H. E., and Mclnerney, T. J., ''Cooling milk," Cornell 
Reading Courses, Vol. V, No. 102, 1914. 



MILK AND CREAM 19 

slowly in air even though the temperature of the air is 
rather low. • If milk is allowed to cool by standing in a 
cold atmosphere, it will do so unevenly, and by the time 
the milk in the center of the can is cooled, that part near 
the walls of the can may be frozen. The fat is not evenly 
distributed in frozen milk; therefore it is not so good as 
normal milk. 

''1. The bacteria-content of milk held at a temperature 
of 50° F. increases slowly, while the bacteria-content of 
milk held at 90° F. increases rapidly. 

"2. At a temperature of 90° F. bacteria increase rapidly 
in milk that had either a small or a large amount of bac- 
teria in it originally. 

"3. Cooling milk by placing the cans in a tank of ice 
water is a practical method for use in farm dairies. To 
cool the milk rapidly it must be stirred at frequent inter- 
vals. 

"4. Stirring the milk at intervals of five minutes 
caused a sufficiently rapid drop in temperature. Ra- 
pidity of coohng due to stirring the milk at intervals of 
five minutes and at intervals of ten minutes was very 
slight. 

"5. When sufficient quantities of ice were used, stirring 
the water in the cooling tank had little effect on the 
rapidity of cooling. 

"6. In order to obtain the best efficiency from the 
conical type of cooler, it is absolutely necessary to stir 
the water inside the cooler. 

"7. Lower temperatures can be obtained by using 
brine and ice than with ice water alone." 

Stocking * shows the effect of temperature on the de- 

* Stocking, W. A., Jr., ''Problems of the milk producers," N. Y. 
State Dept. Agr., Circ. 10, 1910. 



20 THE BOOK OF ICE-CREAM 

velopment of the bacteria in milk by the following experi- 
ment: A sample of milk, which was thoroughly mixed, 
was divided into six equal parts. The six bottles were 
placed in water at different temperatures for twelve 
hours, at which time the germ-content of each lot was 
determined. The six bottles were then all placed to- 
gether in a temperature of 70 degrees and allowed to 
remain until they curdled. As each sample curdled, the 
time was recorded. The difference in the germ-content 
and the keeping time is the result of the difference in 
temperature for a period of twelve hours only, and shows 
what may happen easily in milk which is allowed to stand 
overnight without thorough cooling. 

Table I 

Effect of different temperatures for twelve hours on the growth 
of bacteria and on the keeping quality of milk 

I II 

Kept at 45 degrees Kept at 50 degrees 

Number of bacteria 9,300 Number of bacteria 18,000 

Curdled in 75 hours Curdled in 72 hours 

III IV 

Kept at 55 degrees Kept at 60 degrees 

Number of bacteria 38,000 Number of bacteria 453.,000 

Curdled in 49 hours Curdled in 43 hours 

V VI 

Kept at 70 degrees Kept at 80 degrees 

Number of bacteria 8,800,000 Number of bacteria 55,300.,000 

Curdled in 32 hours Curdled in 28 hours 

14. Milk and cream production and handling. — The 

following diagram shows the main sources of contamina- 
tion and the undesirable methods of handling by which 
the quality of milk and cream is impaired : 



MILK AND CREAM 



21 



Sources of contamination and undesirable methods of handling 

Atmosphere in the stable I Dust from feed 

' Dust irom floor and beddmg 



On the 
'farm 



Cows 



Utensils 



Milker 



Exterior of udder and flank 
[ Coat 

Dirty utensils 
Rusty utensils 

Dirty clothes 
Dirty hands 
Wetting the teats 



ri 1- . [ Air and dust 

Cooling I j^j^^y ^^^^^ 

Transportation from farm to creamery 



Creamery ■ 



Careless methods 



Transportation from 
creamery to ice-cream 
manufacturer 



Ice-cream manufacturer 



Exposed to sun and dust 
Carried in dirty utensils 

Allowing milk to stand before 

separating 
Allowing cream after separated 
to stand before cooling 
I Not cooling cream to low 
[ enough temperature 
Dirty equipment 

Use of dirty rusted cars. Allowing to 
stand on railroad platforms, in the 
sun uncovered 

Lack of can jackets 

Poor delivery service 

Lack of refrigerator cars 

Too long shipments 

Holding cream too long 

Lack of refrigerator space to hold cream 

Dirty equipment and utensils 



The above shows that the producer controls most of 
the factors which concern the sources of initial contami- 
nation.* After the milk leaves the producer, if it is not 

* Ayres, S. H., Cook, L. B., Clemner, P. W., "The four essential 
factors in the production of milk of low bacterial content," U. S. 
Dept. Agr., Bui. 642, 1918. 



22 



THE BOOK OF ICE-CREAM 



properly handled, the organisms in it may develop or if 
exposed to dirty conditions more contamination may take 
place. The important factors in the production and 
handling of milk are: clean utensils, clean healthy cows, 





Fig. 3. — Sharpies milk 
clarifier. 



Fig. 4. — De Laval milk clarifier 
turbine drive. 



small-top milk-pails, proper cooling and maintaining of 
low temperature, 50° F. or below. The importance of 
can jackets to aid in keeping the cream cold should not 
be overlooked, especially when shipping in hot weather. 
The quality^ of the milk and cream is largely determined 
by the time it is delivered at the ice-cream plant. 

15. Clarifier. — If solid or semi-solid dirt either visible 



MILK AND CREAM 23 

or invisible is in the milk, it can be removed by the use 
of a clarifier. This is a specially devised machine (Figs. 
3 and 4) which takes out the dirt by centrifugal force. 
It is desirable to clarify milk and cream for ice-cream- 
making. Besides removing dirt which gets into the milk 
during handling, the clarifier also takes out blood cor- 
puscles and pus cells which are sometimes secreted with 
the milk. 

16. The chemical composition of the milk and cream. — 
It is not possible here to discuss in detail the composi- 
tion of the milk and cream and the factors influencing 
it. Ross * gives the composition of milk, cream and 
skimmed-milk as follows: 

Table II 

Showing composition of milk 

Average Maximum Minimum 

Water 87.0 90.69 80.32 

Sugar 

Fat 

Casein 

Albumen 

Ash 

Table III 

Showing composition of cream 

Cream high in fat Cream low in fat 

Water 29.0 76.6 

Fat 67.5 •.15.2 

Casein 



5.0. ... 


. . 6.03.... 


.. 2.11 


4.0..., 


, .. 6.47..;. 


. . 1.67 


2.6..., 


. . 4.23.... 


.. 1.79 


0.7. ... 


. . 1.44.... 


. . .25 


0.7..., 


... 1.21..., 


. . .35 



.„ ( 1.2 3.1 

Albumen j 

Sugar 2.2 4.5 

Ash 0.1 0.6 

* Ross, H. E., "Composition of milk and some of its products," 
Cornell Reading Course, Vol. 11, No. 32, 1913. 



24 THE BOOK OF ICE-CREAM 

Table IV 

Showing composition of skimmed-milk 

Water 90.60 

Fat 10 

Sugar 4 . 95 

Casein 3 . 15 

Albumen 42 

Ash 78 

From the view po'nt of the ice-cream-maker, the fat 
and solids not fat are of special consideration. Each 
state has standards for milk, cream and skimmed-milk. 
(See Table XV.) The federal standards * are as follows: 
Milk is the fresh clean, lacteal secretion obtained by the 
complete milking of one or more healthy cows, properly 
fed and kept, excluding that obtained within fifteen days 
before and ten days after calving and contains not less 
than eight and one-half (8.5) per cent of solids not fat 
and not less than three and one-quarter (3.25) per cent 
of milk-fat. 

Skim-milk is milk from which a part or all of the cream 
has been removed, and contains not less than nine and 
one-quarter (9.25) per cent of milk solids. Cream is that 
portion of milk, rich in milk-fat, which rises to the surface 
of milk on standing, or is separated from it by centrifugal 
force, is fresh and clean and contains not less than eight- 
een (18) per cent of milk-fat. 

Milk and cream should be purchased on the fat test 
and not by measure, the price being based on the fat- 
content. For method of testing, see Chapter XIV. 

Because of the variable composition of milk and cream, 
it is necessary to standardize them for use in ice-cream- 
making. For method of standardization, see Chapter XIV. 

* Office of the secretary, U. S. Dept. Agr., Circ. 19, 1906. 



CHAPTER III 

MANUFACTURED MILK PRODUCTS AS RE- 
LATED TO ICE-CREAM 

Besides the milk and cream, several other manufac- 
tured milk products are used in ice-cream. What has 
been said previously about the milk and cream applies 
also to the milk for these products. The quality, es- 
pecially the flavor, is very important. 

CONDENSED AND EVAPORATED MILK 

There is a difference between condensed and evapo- 
rated milk, but because of their similarity, both in com- 
position and manufacture, they will be considered to- 
gether. Condensed milk usually has sugar added to 
preserve it, although some ice-cream-makers use it without 
added sugar, when it is known as plain in contrast to 
sweetened condensed milk. The evaporated milk is 
usually sterilized in sealed cans to preserve it, no sugar 
being added. More condensed milk is employed in mak- 
ing ice-cream than evaporated milk. The condensed is 
usually shipped to the ice-cream manufacturer in bulk, 
either in milk-cans or barrels. 

17. Method of manufacture. — The water is removed 
from the milk by heating under reduced pressure. The 
heating is usually done in a copper pan. (Fig, 5.) This 
is accomplished by means of a steam jacket on the bottom 
and usually one or two steam coils in the pan. Before 

25 



26 



THE BOOK OF ICE-CREAM 



drawing the milk into the pan, it is heated in an open 
copper vessel, by turning direct steam into the milk. 
This container is called the hot well or fore warmer. The 
temperature varies according to whether plain or sweet- 
ened condensed is being made. The sweetened is heated 




Fig. 5. — View of modern condensory showing hot wells, vacuum pan, 
vacuum pump and cooling tanks. 



higher to dissolve the sugar. The object of heating under 
reduced pressure is to reduce the boiling point. At ordi- 
nary pressure milk would boil at the same temperature 
or a little above that of water. At this temperature the 
milk could not be condensed without imparting a pro- 
nounced cooked flavor and caramelizing a part of the sugar. 
The vacuum in the pan is produced by means of a 



MANUFACTURED MILK PRODUCTS 27 

vacuum pump. A vacuum equal to a column of mercury 
about 25 inches is usually maintained. The condenser 
is located at the top of the pan and is directly connected 
with it. As the milk boils, the vapor passes from the pan 
into the condenser. In the latter the vapor comes in 
contact with a spray of cold water which causes it to 
condense. The pump carries off the condensing water 
and the condensed vapor. When the desired density is 
reached, the milk is drawn from the pan and cooled. The 
proper concentration of the milk is determined by a 
special graduated scale known as the Baume. A more 
recent method is an electric resistance. If sweetened 
condensed is being made, the sugar is added to the milk, 
the mixture of sugar and milk are heated to dissolve the 
sugar before drawing them into the pan. 

Sometimes the milk is superheated; this consists of 
turning live steam into the milk just at the time that the 
desired concentration is reached. It gives the condensed 
milk more of a '4ivery" appearance, which is probably 
due to the precipitation of the albumen. 

The length of time required for condensing the milk 
to the desired consistency varies with the amount of 
milk in the pan, amount of heating surface, size and 
capacity of vacuum pump, and amount and temperature 
of water in the condenser. 

18. Standards for condensed milk. — The following 
standards are given by the United States Department 
of Agriculture: * 

''Sweetened condensed milk, sweetened evaporated 
milk, sweetened concentrated milk, is the product result- 
ing from the evaporation of a considerable portion of the 

* Office of the Secretary, U. S. Dept. Agr., Food Inspection, De- 
cision 170, 1917. 



28 THE BOOK OF ICE-CREAM 

water from the whole, fresh, clean, lacteal secretion 
obtained by the complete milking of one or more healthy 
cows, properly fed and kept, excluding that obtained 
within fifteen days before and ten days after calving, to 
which sugar (sucrose) has been added. It contains, all 
tolerances being allowed for, not less than twenty-eight 
per cent (28.0 per cent) of total milk solids, and not less 
than eight per cent (8.0 per cent) of milk fat. 

"Condensed skimmed milk, evaporated skimmed milk, 
concentrated skimmed milk, is the product resulting from 
the evaporation of a considerable portion of the water 
from skimmed milk, and contains, all tolerances being 
allowed for, not less than twenty per cent (20.0 per cent) 
of milk solids. 

"Sweetened condensed skimmed milk, sweetened evap- 
orated skimmed milk, sweetened concentrated skimmed 
milk, is the product resulting from the evaporation of a 
considerable portion of the water from skimmed milk to 
which sugar (sucrose) has been added. It contains, all 
tolerances being allowed for, not less than twenty-eight 
per cent (28.0 per cent) of milk soHds." 

Condensed or evaporated milk should be purchased 
only on its composition, both fat and solids not fat. For 
method of testing, see Chapter XIV. 

19. Conditions essential for a milk condensory.* — 
"First. The plant should be located in a community 
which is not only thoroughly adapted in every way to a 
high standard of extensive dairy farming, but is already 
far advanced in such development. The herds of cows 
should be large, healthy, well cared for, and of a breed 
or breeds that produce a grade of milk reasonably adapted 

* These conditions are taken from the U. S. Dept. Agr., Weekly 
News Letter, Vol. II, No. 45. 



MANUFACTURED MILK PRODUCTS 29 

for* condensing purposes and the production of a standard 
product. 

''Second. In establishing a plant for condensing milk 
by the vacuum process it is of primary importance that 
the location provide an abundant, steady supply of pure, 
cold water, independent of the supply required for boiler 
use. The quantity of water required to condense a given 
quantity of milk will, of course, vary with the operating 
conditions, such, for example, as the temperature of the 
condensing water and the temperature (or the pressure) 
of the vapor to be condensed. A general idea of the 
importance of water supply can be obtained from the 
authoritative estimate that about 3 gallons of water 
are required for the condensing of one pound of fresh 
milk (about one pint). Difficulty in obtaining an ade- 
quate supply of good, pure, cold water is a cause of serious 
embarrassment to some of the commercial condensories 
now established, and the lack of it has been the cause of 
many failures. 

''Third. An abundant supply of milk is an absolute 
necessity. The exact quantity required daily will, of 
course, vary with the size of the plant. Several reliable 
authorities have estimated that for the profitable pro- 
duction of condensed milk on a commercial scale the 
supply of raw milk to the factory should not fall below 
15,000 pounds a day. This estimate is exclusive of the 
daily supply of milk normally required for other purposes 
by the community. Furthermore, if the finished product 
is to be of marketable quality, the milk received at the 
condensory must be of exceptionally high grade; that is, 
clean and pure. While first-class milk is essential for the 
manufacture of a first-class dairy product of any kind, 
it is absolutely necessary if a condensed milk factory is to 



30 THE BOOK OF ICE-CREAM 

be a success. If a few cans of low-grade milk are not 
detected at the receiving platform of a condensory, the 
slight defects in the raw milk are multiplied in the process 
of condensing it, and the result is practically certain to 
be the complete loss of the whole batch, which may 
represent a financial loss of several hundred dollars. This 
statement may be illustrated concretely: It is claimed by 
authorities that raw milk containing as much as 0.2 per 
cent acid (calculated as lactic acid) is not fit for condens- 
ing purposes. This does not necessarily mean that it 
would taste sour, but if accepted and condensed in the 
ratio of 2.25 to 1 (it may be more but is seldom less), the 
acidity, increasing in the same ratio, would reach 0.45 
per cent, which would be practically certain to cause a 
sour taste in the finished product. Every housewife 
knows that sour milk will coagulate or curdle on heating, 
and that the higher the temperature the more rapid is 
the curdling process and the finer the curd. This makes 
it unfit for cooking purposes. In the commercial pro- 
duction of evaporated milk, the product must be sterilized 
in the cans at a very high temperature in order to insure 
a good keeping quality. It is obvious, therefore, that if 
milk is delivered to the factory with a slight excess of 
acidity, it would probably be impossible to sterilize the 
product obtained from it without producing a hard curd, 
which would make the product absolutely unsalable, and 
thus a total loss to the manufacturer. Furthermore, 
excessive acidity, which is principally caused by im- 
proper care and handling of the milk, is not the only 
condition that may render milk unfit for condensing. 
Other undesirable qualities of the milk may also be 
induced by poor health and improper care of the cows, 
by the kind and the condition of their feed, and by 



MANUFACTURED MILK PRODUCTS 31 

many other details of imperfect management of the 
dairy farms. 

''The services of experts thoroughly qualified by train- 
ing and long experience in this particular line will be 
required to detect and guard against these unfavorable 
conditions. 

''Fourth. Adequate facilities for marketing constitute 
another essential to the commercial success of a condensed 
milk plant. Commercial success, of course, implies a 
profitable market for the product — a market which is 
readily and directly accessible to the plant without adding 
excessively to the , cost of manufacture, either in the form 
of high freight rates or long hauls from the condensory 
to a railroad. As already indicated, the successful manu- 
facture of condensed milk on a commercial scale requires 
a large output of the finished product — a very much 
larger output than is likely to be consumed in the local 
market; therefore, in selecting a location, favorable 
transportation facilities to a good market or markets are 
a consideration of vital importance to ultimate success. 

'' Fifth. In establishing and operating a condensory, 
the necessity of adequate capital is another important 
question. The cost of buildings and equipment will, of 
course, vary with the purchase of superior or inferior 
materials and workmanship, as well as size of the plant, 
and, in some measure, the kind of condensed milk to be 
produced. In any case, however, the buildings should . 
be thoroughly substantial, more so than is commonly 
considered necessary for a creamery or a cheese factory. 
The major part of the equipment is a very highly special- 
ized, more or less complicated, and very expensive type. 
The proper operation of the equipment, especially the 
vacuum pan, and the sterilizer when the product is steril- 



32 THE BOOK OF ICE-CREAM 

ized in cans, calls for a high degree of skill and large 
experience, if serious losses are to be avoided and a stand- 
ardized legal product is to be produced. The cost of 
buildings, equipment, and operation of a plant for the 
manufacture of evaporated milk (unsweetened condensed 
milk for household use) will illustrate the capital required 
for the manufacture of any other form of condensed milk. 
Some reliable authorities have conservatively estimated 
that adequate buildings and equipment for a minimum 
production on a commercial scale would cost in the 
neighborhood of $25,000, exclusive of working capital. 
The markets for condensed milk at best are very unstable. 
Frequently, the manufactured product must be held 
several months before it is marketed. In the meantime, 
the plant must be kept in operation, for which a very 
considerable surplus capital must be provided. The 
same authorities estimate this item at $10,000. It there- 
fore appears that in establishing and operating a milk 
condensory, capital to the amount of at least $35,000 
must be provided. That this estimate is conservative is 
indicated by the fact that manufacturers of condensed 
milk have stated that a capital of $50,000 is usually 
necessary to operate a condensed milk factory. 

"Sixth. Commercial success in any manufacturing 
enterprise usually requires much more than merely plac- 
ing the product upon the market. A demand for the 
product must be firmly established and a regular trade 
developed before success is assured. To attain such a 
result the new product must meet the keen competition 
of similar products already well established. There are 
many well-established brands of condensed milk now on 
the market. There may be room for many more, but 
new brands, regardless of their quality, must expect to 



MANUFACTURED MILK PRODUCTS 33 

overcome strong competition before a firm foothold is 
gained. This usually requires extensive advertising and 
a competent, vigorous sales force, which entails a heavy 
expense. Good salesmanship and advertising must be 
continued. The necessity of a thoroughly organized 
seUing organization should, therefore, not be overlooked.'' 

20. Supply of condensed milk for the ice-cream 
plant. — From the above conditions essential for a conden- 
sory, it is evident that an ice-cream plant would not be jus- 
tified in trying to operate one, unless also they maintained 
a large milk and cream receiving plant in the country. It 
is the usual practice for the ice-cream manufacturer to 
purchase the supply of condensed milk. However, some 
plants have a condensory in connection with their country 
plant, which is operated successfully. When the supply 
of condensed milk is purchased, the basis of payment 
should be the composition. For the methods of testing 
condensed milk, see Chapter XIV. 

MILK POWDER 

In certain localities, especially the South where it is 
hard to secure milk and cream, milk powder and butter 
are often emulsified or homogenized to make cream. 
Milk powder is also employed in the same way to meet 
sudden demands for cream. Milk powder is often used 
in ice-cream to increase the milk solids not fat and thereby 
give a firmer body and a smoother texture. The com- 
position varies in fat from skim to whole milk. 

21. Standards for milk powder. — The following stand- 
ards are given by the United States Department of 
Agriculture :* 

* Office of the Secretary, U. S. Dept. Agr., Food Inspection De- 
cision 170, 1917. 



34 THE BOOK OF ICE-CREAM 

''Dried milk is the product resulting from the removal 
of water from milk, and contains, all tolerances being 
allowed for, not less than twenty-six per cent (26.0 per 
cent) of milk fat, and not more than five per cent (5.0 
per cent) of moisture. 

''Dried skimmed milk is the product resulting from 
the removal of water from skimmed milk and contains, 
all tolerances being allowed for, not more than five per 
cent (5.0 per cent) of moisture." 

22o Powdered milk processes. — Two patented proc- 
esses of making powdered milk are in general use in 
this country at the present time, the Merrell-Soule and 
the Ekenberg. 

23. Merrell-Soule powdered milk.* — "The desired 
process must, it was evident, be one which would not af- 
fect the active principles or the nutritive qualities of 
milk, nor change its chemical reactions in any way. The 
product when reaching the consumer must be, in every 
essential quality, fresh milk. 

"The methods known as condensation and evapora- 
tion, also the earlier milk powder processes, were efforts 
to achieve the desired result. But in none of them was 
the goal completely attained, as it is to-day in Merrell- 
Soule Powdered Milk — the product of a perfected 
process. 

"Liquid Milk is seven-eighths water. Merrell-Soule 
Powdered Milk contains approximately 2 per cent of 
moisture. Transportation cost is thus reduced to a very 
small percentage of the expense of shipping liquid milk. 
The fact that powdered milk may be shipped by freight, 

* This article is taken from the publication, ''Merrell-Soule Pow- 
dered Milk for the Dairy, Creamery and Ice Cream Plant," Merrell- 
Soule Co., Syracuse, N. Y., 1918. 



MANUFACTURED MILK PRODUCTS 35 

while liquid milk must go by express or baggage, means 
an additional saving. 

''The expense of shipping powdered milk is also, of 
course, much lower than the transportation cost of the 
condensed product. 

"The Merrell-Soule process reduces the bacteria count 
to a remarkably low figure, and it is a demonstrated fact 
that the bacteria which are to be found in the fresh-made 
powder tend to die off, rather than propagate, during 
storage. 

"Merrell-Soule Powdered Milk is quickly and easily 
dissolved in water, and the 'reconstituted' liquid milk 
thus obtained is pure, fresh milk, with the delicate odor 
and unmistakable flavor of fresh milk, and with every 
chemical reaction and nutritive property of fresh milk 
retained unchanged . " 

24. History of Merrell-Soule process. — "The history 
of powdered milk dates back to the middle of the last 
century, when an inventor named Grimwade patented, in 
England, the first commercially usable process. 

"He added carbonate of soda to fresh milk, evaporated 
it in open-jacketed pans, with constant agitation, until 
a dough-like substance resulted; added cane sugar, 
pressed the mixture between rollers into ribbons, dried it 
still further, then pulverized it. 

"This process, cumbersome and unsatisfactory as it 
must have been, was in practice for some years. Other 
processes followed at intervals for half a century, but the 
real commercial development of the industry dates back 
only about twenty years. 

"It was in 1899 that a machine for the drying of milk 
by what has since become known as the 'double roll' 
process was invented by W. B. Gere, since deceased, then 



36 THE BOOK OF ICE-CREAM 

secretary of the Merrell-Soule Co., and I. S. Merrell, 
first vice president of the company. But the 'dry milk^ 
which resulted from this process was not satisfactory, and 
for that reason was not put on the market by the Merrell- 
Soule Company. 

''Several other processes were then tried out, but none 
proved satisfactory until Lewis C. Merrell, brother of 
I. S. Merrell, hit upon the spraying of milk into a regu- 
lated current of heated air. This gave the quality that 
had been desired, and the next thing was to determine 
the commercial value of the process. 

"In January, 1905, a building owned by the Merrell- 
Soule Company at Fayette ville, N. Y., was equipped, 
and powdered milk was produced, in a small way, by this 
spray process. Enough was marketed, and with suf- 
ficiently gratifying results, to warrant the company in 
going ahead with the enterprise. 

"Meantime, patents had been applied for, and the 
patent office had referred the Merrell-Soule Company 
to a United States patent granted in 1901 to Robert 
Stauf, of Posen, Germany, which seemed to cover the 
process. F. C. Soule, president of the Merrell-Soule 
Company, thereupon went to Germany and bought not 
only the United States patent held by Stauf, but also 
thirteen foreign patents owned by Stauf and his associates. 

"The wisdom of the purchase of all the patents held 
by the Stauf interests has since been amply demonstrated. 
In 1915, patent litigation which had been in the courts 
for three years was decided by the Court of Appeals in 
favor of the Merrell-Soule Company, the decision being 
based on this company's possession not only of its own 
patents, but also of the basic patents governing the spray 
process of powdered milk manufacture. 



MANUFACTURED MILK PRODUCTS 37 

''Following the success of the experiment at Fayette- 
ville, the construction of the first Merrell-Soule Powdered 
Milk factory, at Arcade, N. Y., was begun in 1906. Be- 
fore this factory was completed, it had been discovered 
that a better product could be obtained by condensing 
the milk in a vacuum pan before spraying. This resulted 
in new patents covering what was known as the Merrell- 
Gere process, embodying the original Stauf method and 
the improvement mentioned. 

"Since then many other improvements have been 
made at the Merrell-Soule plants, many other patents 
taken out. The first powdered milk factory, at Arcade, 
was followed by a second, at Little Valley, N. Y., in 
1909. Since then factories have been established at 
Frewsburg, N. Y., Union City, Pa., Waterford, Pa., 
Farmersville Station, N. Y., Warsaw, N. Y., Gainesville, 
N. Y., Attica, N. Y., and Omaha, Neb. 

''Consumption of milk has increased from 18,000 
quarts per day, in 1906, at Arcade, to 300,000 quarts per 
day, at the present time, in the ten factories. The output 
of powdered milk has grown from 2,500 pounds per day, 
twelve years ago, to a present capacity of 50,000 pounds 
per day. 

"These products include Powdered Skimmed Milk, 
Butterfat Powders, of varying butterfat content, 'Cream 
PowderSjV which contain up to 72 per cent, butterfat, and 
Powdered Buttermilk.'' 

25. Uses of Merrell-Soule powder in ice-cream. — " The 
ice-cream manufacturer demands a milk or cream prod- 
uct which is clean, which will not sour quickly, which is 
not a breeder of bacteria, and which gives him the largest 
percentage of milk solids in proportion both to its bulk 
and its cost. All these essentials he finds in Merrell- 



38 THE BOOK OF ICE-CREAM 

Soule powdered milk. Its powdered form insures the 
greatest possible purity and cleanness, as is attested by 
many authorities. There need be no loss through sour- 
ing, no sticky, half-empty cans standing around, gather- 
ing flies and breeding bacteria, when Merrell-Soule 
powdered milk is used. The ice-cream man makes up 
just what he needs for the day's business. He can make 
up a big supply of cream, for a sweltering day's run, or 
a small amount for a cool day. A sudden drop in tem- 
perature will not leave him with a lot of cream on hand 
that must either be used or spoiled. It has been proved 
that Merrell-Soule powdered milk shows a far smaller 
bacteria count than any other form of milk, and it offers 
no breeding place for microbes. 

''Merrell-Soule powdered milk can be put to many 
uses in the ice-cream factory: — 

''1. In the production of milk or cream from powdered 
skimmed milk, butter and water. 

''2. The production of skimmed milk from powder 
and water. 

"3. The standardization of the milk solids in the ice- 
cream batch. 

"4. Furnishing the necessary skimmed milk solids. 

''5. Blending butter and the powdered skimmed milk 
with liquid whole milk of any fat content, for the com- 
plete total milk solids of the batch. 

"Other uses could be mentioned, but these will give 
the ice-cream maker an idea of the importance of Merrell- 
Soule powdered skimmed milk in his business. 

"Many of the large ice-cream makers are beginning to 
realize the losses which they incur every year through 
using condensed milk to raise the per cent of milk solids 
in their ice-cream. 



MANUFACTURED MILK PRODUCTS 39 

"By the use of powdered skimmed milk they have an 
easy and accurate means of holding the solids to any 
desired percentage. 

" Merrell-Soule powdered skimmed milk does not take 
the place of gelatines, ice-cream powders and the like,which 
prevent the ice crystals in ice-cream, but it does provide 
the solids, not fats, which give ^body and texture' to 
the ice-cream and makes it smooth, velvety and palatable. 

'^ Almost every ice-cream maker has his own formula 
for his mix, which gives the best satisfaction to the trade 
he serves, and for this reason we will not print any ice- 
cream formulas. We will be glad, however, to furnish 
formulas which have given good results, to any ice-cream 
maker who applies to us. 

"In our own experimenting, and in practical work in 
some of the large ice-cream factories, we have found the 
powdered skimmed milk to be a wonderful help to ice- 
cream makers in a great many ways." 

26. Ekenberg powdered milk.* — "The Ekenberg proc- 
ess was invented by Dr. Martin Ekenberg of Stockholm, 
Sweden. Dr. Ekenberg had experimented with milk 
drying for some years, and his father, who was an eminent 
chemist, also, had devoted considerable time to this 
problem. 

"The Ekenberg process is the result of these investi- 
gations, and the machine which Dr. Ekenberg invented, 
he called the Ekenberg Exsiccator. This consists of a 
single drum with conical shaped ends, revolving in a 
vacuum chamber. The milk is introduced into the cham- 
ber through various pipes and is sprayed into the conical 
or bowl shaped ends of the revolving drum, — the drum 

* This description was given by L. P. Bennett, president of the 
Ekenberg Co., Cortland, N. Y. 



40 THE BOOK OF ICE-CREAM 

being heated by steam at a low temperature. The vac- 
uum maintained in the chamber, is from 25 to 27 inches, 
and as a result, the temperature in the chamber is low, 
not exceeding 100° F. 

"The milk upon being introduced into the bowl shaped 
ends is evaporated to a considerable degree and then 
passes off into the suction pipe of a pump, from which the 
milk is again introduced into the vacuum chamber, this 
time upon the periphery of the drum, to which it adheres, 
and is then removed by a series of scrapers or knives. 
It will be seen that the milk is only upon the drum during 
about two-thirds of one revolution. The dried product 
falls into another chamber which is separated from the 
main vacuum chamber by a series of air locks, so that it 
may be removed at will from the exsiccator, without 
stopping the continuous working of the machine. 

"When the dried product is removed, its condition is 
that of light fluffy flakes. It is then allowed to stand in 
a chamber heated to about 90° F. for about one hour, 
during which time, the lactose crystallizes. From this 
chamber it is removed, and then milled in the same man- 
ner as wheat is milled in the manufacture of wheat flour." 

27. Uises of Ekenberg powder in ice-cream. — " Ekenflor 
is the trade name given to the many grades of powdered 
milk made from skimmed milk, partly skimmed milk, 
or whole milk. In using Ekenberg Powdered Milk for 
ice-cream it is not necessary to change the present formu- 
las, but only to adapt then to the use of milk in dry form. 
• "The raw milk from which Ekenflor is made is drawn 
from inspected dairies and is manufactured in clean 
sanitary factories and is therefore of the finest quality. 

"Ekenflor does not sour or draw flies, and its use by 
the ice-cream maker can not fail to reduce the chance of 



MANUFACTURED MILK PRODUCTS 41 

unsanitary conditions in his factory and his losses from 
spoiled milk. 

^' There is always 'sl feast or a famine' in the raw-milk 
market, and as our powdered skimmed milk keeps almost 
indefinitely without cold storage, it is always ready for 
immediate use, no matter how sudden or great the de- 
mand may be. Its use makes the ice-cream manufac- 
turer independent of his local supply of milk or cream or 
condensed milk and of the local prices." 

28. Butter. — ^For the making of emulsified or homo- 
genized cream, butter is ordinarily employed to supply 
the milk-fat. Unsalted butter that is clean flavored and 
made from clean cream is to be desired. If the butter is 
produced from inferior cream or has any undesirable flavor, 
the cream made from it will have the same undesirable 
flavor. 

It is the usual practice to store the butter during the 
period of low prices,' which is commonly the summer, and 
then to use it when prices are high, usually the winter. 
The question of the kind of butter and method of storage 
is a very vital one. It is generally considered that sweet 
cream butter holds better in storage. The temperature 
of storage should be as near 0° F. as possible. 

The successful storing of buttei; requires an intimate 
knowledge both of market conditions and the desired 
quality of butter for storage. The daily prices and move- 
ments of butter, in and out of storage, and the daily 
receipts in the different markets and the sales, may be 
obtained from the daily and weekly reports made by the 
Bureau of Markets, United States Department of Agri- 
culture. In New York City, the market reports are also 
made in the ''Price Current," published by the Urner 
Barry Company. Before storing butter, these reports 



42 THE BOOK OF ICE-CREAM 

should be studied carefully, to make sure that the market 
conditions will warrant storage. The quality of the butter 
can be determined by the market grades or by the actual 
examining by an expert butter judge. Usually when the 
ice-cream manufacturer purchases butter for storage, 
the quality will be determined by the market grade, as 
personal examination is seldom possible. 



CHAPTER IV 

SUGAR, CHOCOLATE PRODUCTS, FRUITS, 
STABILIZERS AND FILLERS 

Besides the milk products, a number of other materials 
are used in ice-cream. These are embodied in small 
amounts but their quality is of vital importance. For 
this reason they are briefly discussed. 

29. Sugar. — For sweetening the ice-cream, granulated 
sugar is usually employed. This may be either cane- 
or beet-sugar, and should be free from all visible dirt. 
Sugar seems to contain many mold spores and so should 
be examined to determine the presence of mold or bac- 
teria. However, during the war, in order to conserve the 
supply of granulated sugar, various substitutes were 
used, such as corn sirup, invert sugar, honey and maple 
sirup. 

30. Invert sugar. — Ruehe * gives the following direc- 
tions for making invert sugar: 

''Cane sugar (or beet sugar) can be inverted by the 
simple process of heating in the presence of an acid. The 
chemical reaction that takes place results in the same 
products being formed as are formed when the sugar 
(sucrose) is taken into the human body, the sugar forming 
equal parts of dextrose and levulose. The following 
formula may be used in making invert sugar syrup of 

* Ruehe, H. A., " Conserving sugar in ice cream manufacture," 
El. Exp. Sta. Circ. 219, 1918. 

43 



44 THE BOOK OF ICE-CREAM 

such sweetness that a pound of the syrup will replace a 
pound of sugar: 

100 pounds of sugar 
44 pounds of water 
50 grams of powdered tartaric acid 

These ingredients are mixed together and boiled for 30 
to 35 minutes. If boiled longer than 35 minutes, the 
syrup darkens in color and a flavor develops which tends 
to make the syrup resemble glucose syrup, and this is 
somewhat undesirable. This solution boils at a tem- 
perature of about 221 degrees Fahrenheit. A steam 
pressure kettle can be used very satisfactorily or an open 
candy kettle over a steady fire may be used. If the solu- 
tion is boiled too vigorously, there will be too large a 
loss by evaporation. Ordinarily the loss will be from 
3 to 5 per cent. 

"The above formula should make 140 pounds of syrup, 
and if there is considerable loss due to evaporation, the 
syrup can be brought up to this weight by the addition 
of water. The resultant invert sugar syrup is not unlike 
strained honey in appearance and taste. It contains 
about 71.4 per cent of sugar and it tastes considerably 
sweeter than a sugar syrup of the same strength. It does 
not crystallize, and it mixes readily with the ingredients 
of the ice cream. It can be used in the same proportions 
as sugar, the amount necessary for ten gallons of ice 
cream being 6.5 to 7 pounds. It gives very satisfactory 
results in freezing and a pleasant flavor in the finished 
product. 

"It can be readily seen that by using the above method 
the sugar supply can literally be stretched, for with only 
71.4 per cent as much sugar as is now being used in ice 
cream, the same degree of sweetness can be obtained." 



SUGAR, CHOCOLATE PRODUCTS, ETC. 45 

31. Sugar-saving substitutes. — Frandsen,* while work- 
ing on sugar-saving substitutes, reached tlie following 
conclusions: 

'^1. Four formulas have been worked out which save 
from 30 per cent to 50 per cent of cane sugar in the mix : 

I. 44 lbs. 17 per cent cream 
4 lbs. cane sugar 
1% lbs. corn syrup (glucose) 
4 oz. vanilla 
4 oz. gelatine 

II. 44 lbs. 17 per cent cream 
2.9 lbs. cane sugar 
2 . 9 lbs. corn syrup 
4 oz. vanilla 
4 oz. gelatine 

III. 44 lbs. 17 per cent cream 

13^ lbs. cane sugar 
43^ lbs. invert sugar 
4 oz. vanilla 
4 oz. gelatine 

IV. 44 lbs. 17 per cent cream 

13^ lbs. corn syrup 
13^ lbs. invert sugar 
234 lbs. cane sugar 
4 oz. gelatine 
4 oz. vanilla 

''2. The ice cream prepared according to these four 
formulas meets the requirements of good ice cream. 

''3. Corn syrup dissolves with difficulty in cold cream. 
When added to cream before pasteurizing, it dissolves 
readily. 

"4:. In hydrolyzing the syrups, excessive heating 
should be avoided. 

* Frandsen, J. H., Rovner, J. W., and Luithly, John, "Sugar-saving 
substitutes in ice cream," Neb. Exp. Sta., Bui. 168, 1918. 



46 THE BOOK OF ICE-CREAM 

"5. When invert sugar and corn syrup are used as the 
only source of sweetening, a rather noticeable syrupy 
flavor is imparted to the ice cream. 

"6. When invert sugar, cane sugar and corn syrup are 
used in the proportions indicated in Formula No. 4, no 
objectionable flavor is noticeable. 

''7. It is thought that hydrolyzing corn syrup in the 
presence of an acid will enhance its sweetening properties. 

'^8. In addition to saving cane siigar, all four formulas 
lower the cost of sweetening per gallon of ice cream. 

"9. Corn sugar can replace 50 per cent of cane sugar 
in the mix. 

''10. None of the substitutes so far tried will satis- 
factorily replace all the cane sugar in the ice cream mix." 

32. Cocoa and cocoa products. — The various choco- 
late and cocoa preparations are manufactured from the 
bean of the tree Theohroma Cacao, of the family of Ster- 
culiacese. This tree averages 13 feet in height, and its 
main trunk is from 5 to 8 inches in diameter. It is a 
native of the American tropics, being especially abundant 
and growing under best conditions in Mexico, Central 
America, Brazil and the West Indies. 

The cocoa beans of commerce are derived chiefly from 
Ariba, Bahia, Caracas, Cayenne, Ceylon, Guatemala, 
Haiti, Java, Machala, Maracaibo, St. Domingo, Surinam 
and Trinidad. Besides these, the Seychelles and Mar- 
tinique furnish a small amount. 

The plant seeds, or beans, grow in pods, varying in 
length from 23 to 30 centimeters, and are from 10 to 15 
centimeters in diameter. The beans, which are about 
the size -of almonds, are closely packed together in the 
pod. Their color when fresh is white, but they turn 
brown on drying. 



SUGAR, CHOCOLATE PRODUCTS, ETC. 47 

The gathered pods are first cut open, and the seeds 
removed to undergo the process of "sweating" or fer- 
menting, which is conducted either in boxes or in holes 
made in the ground. This process requires great care 
and attention, as on it depends largely the flavor of the 
seed. The sweating operation usually takes two days, 
after which the seeds are dried in the sun until they 
assume their characteristic warm red color, and in this 
form are shipped into our markets. 

33. Manufacture of chocolate and cocoa. — For the 
production of chocolate and cocoa, the beans are cleaned 
and carefully roasted, during which process the flavor is 
more carefully developed, and the thin, paper-like shell 
which surrounds the seed is loosened and is very readily 
removed. The roasted seeds are crushed, and the shells, 
which are separated . by winnowing, form a low-priced 
product, from which an infusion may be made having a 
taste and flavor much resembling chocolate. 

The crushed fragments of the kernel or seed proper are 
called cocoa nibs, and for the preparation of chocolate 
they are finely ground into a paste and run into molds, 
either directly or after being mixed with sugar and vanilla 
extract or spices, according to whether plain or sweet 
chocolate is the end product. 

For making cocoa, however, a portion of the oilor fat 
known as the cocoa butter is first removed, by subjecting 
the ground seed fragments to hydraulic pressure, usually 
between heated plates, after which the pressed mass is 
reduced to a very fine powder, either directly or by treat- 
ment with ammonia or alkalies, to render the product 
more soluble. It is held that the large amount of fat 
contained in the cocoa seeds (varying from 40 to 54 per 
cent) is difficult of digestion to many, such as invalids 



48 THE BOOK OF ICE-CREAM 

and children, and hence the desirabihty of removing 
part of the fat. 

34. Composition of cocoa products. — The chief con- 
stituents of the raw cocoa bean, named in the order of 
their relative amount, are fa|}, protein, starch, water, 
crude fiber, ash^ theobromine, gum and tannin. In the 
roasting there is reason to believe a volatile substance is 
developed much in the nature of an essential oil, which 
gives to the product its peculiar flavor, and is somewhat 
analogous to the caffeol of coffee. 

Tannin, the astringent principle of cocoa, exists as 
such in the raw bean, but rapidly becomes oxidized to 
form cocoa red, to which the color of cocoa is due. 

35. Adulteration of cocoa products and standards of 
purity. — The following are the United States standards: 
'^ Standard chocolate should contain not more than 3 per 
cent of ash insoluble in water, 3.5 per cent of crude fiber, and 
9 per cent of starch, nor less than 45 per cent of cocoa fat. 

"Standard sweet chocolate and standard chocolate 
coating are plain chocolate mixed with sugar (sucrose), 
with or without the addition of cocoa butter, spices, or 
other flavoring material, containing in the sugar and 
fat-free residue no higher percentage of either ash, fiber 
or starch than is found in the sugar and fat-free residue 
of plain chocolate. 

''Standard cocoa should contain percentages of ash, 
crude fiber, and starch corresponding to those of plain 
chocolate, after correcting for fat removed. 

''Standard sweet cocoa is cocoa mixed with sugar (su- 
crose) containing not more than 60 per cent of sugar, and 
in the sugar and fat-free residue no higher percentage of 
either ash, crude fiber, or starch than is found in the 
sugar and fat-free residue of plain chocolate. 



SUGAR, CHOCOLATE PRODUCTS, ETC. 49 

''The removal of fat, or the addition of sugar beyond 
the above prescribed hmits, or the addition of foreign 
fats, foreign starches, or other foreign substances, con- 
stitutes adulteration, unless plainly stated on the label. 

''The most common adulterants of cocoa are sugar 
and various starches, especially those of wheat, corn and 
arrowroot. Starch is sometimes added for the alleged 
purpose of diluting the cocoa fat, instead of removing 
the latter by pressure, thus, it is claimed, rendering the 
cocoa more digestible and more nutritious. Unless its 
presence is announced on the label of the package, starch 
should be considered as an adulterant. Cocoa shells are 
also commonly employed as a substitute for, or an adulter- 
ant of, cocoa. Other foreign substances found in cocoa 
are sand and ground wood fibre of various kinds. Iron 
oxide is occasionally used as a coloring matter, especially 
in cheap varieties. 

"Such adulterants as the starches and cocoa shells are 
best detected by the microscope. The presence of any 
considerable admixture of sugar is made apparent by the 
taste. Mineral adulterants are sought for in the ash." 

36. Chocolate sirup. — Ice-cream may be flavored by 
pouring a chocolate sirup over it. The following ma- 
terials are used in making the sirup : 

Powdered cocoa, 1 pound 
Sodium chloride, 6^ drams 
Granulated sugar, 16 pounds 
Shredded gelatine, 23^2 ounces 
Vanilla extract, 2^ ounces 

Dissolve the gelatine in 10 pints of cold water, heat 
to the boiling point, then add 15 pounds granulated 
sugar, stirring occasionally until dissolved. Triturate 
1 pound granulated sugar with the powdered cocoa and 



50 THE BOOK OF ICE-CREAM 

sodium chloride until thoroughly mixed, then add to the 
hot solution; boil for ten minutes, stirring constantly; 
strain while hot and when cool, add the vanilla. 

37. Fruits. — Many different fruits may be used to 
flavor ice-cream. The principal ones are pineapple, 
cherry, strawberry, raspberry, lemon, orange, peaches, 
and the like. In their season, the fresh ripe fruit is used 
as a flavoring. For the period when the fresh fruit cannot 
be obtained, the fruit may be canned, preserved without 
chemicals, preserved with chemicals, or dried. Only 
fresh ripe fruits should be employed, whether used fresh 
or held in some manner; since for ice-cream-making the 
fruit must be broken into small pieces, it is often cheaper 
to obtain from canneries small fruits or broken or crushed 
pieces. 

In some of the large ice-cream plants the fruits are 
preserved in large jars (Fig. 6) by the addition of sugar 
and kept cold but not frozen. Fruits preserved in this 
way give the product a flavor similar to fresh fruits. 
Fruit extracts may be derived from the fruit, by frac- 
tional distillation in dilute alcohol. These extracts should 
not be confused with artificial or imitation flavors. The 
latter are often coal tar ethers or esters. In order to 
obtain the desired flavor, it is usually necessary to com- 
bine fruit extracts with the canned and preserved fruits. 

38. Nuts. — Only sound non-rancid nuts should be 
employed to flavor ice-cream. For flavoring, the nut 
meats should be blanched by soaking in hot water, and 
then removing the outer coating or covering; these 
blanched nuts should then be ground. Often broken nuts 
can be secured cheaply. A flavoring extract may be made 
from the nuts. In many respects this is desirable because 
a more pronounced flavor is obtained. For example, 



SUGAR, CHOCOLATE PRODUCTS, ETC. 



31 



pistachio nuts give a very weak extract. It is the custom 
to use pistachio flavoring and color the ice-cream green. 

39. Stabilizers and fillers. — If ice-cream is not con- 
sumed as soon as made, ice crystals will begin to form 
unless some stabilizer is used. This is a substance added 
to ice-cream to prevent the formation of ice crystals 
which cause a grainy bodied product. Stabilizers are 




Fig. 6. — Fruit storage in large ice-cream plant. 

sometimes known as '^ holders" or '^colloids" and com- 
monly as '^binders." A ^^ filler" is some substance added 
to the ice-cream to cheapen it, usually to replace the 
milk-fat and milk solids not fat. A "filler" may serve 
the purpose of a ''binder" or a "stabilizer," but a stabil- 
izer cannot take the place of a "filler." The common 
stabilizers are gelatine and gum tragacanth. The com- 
mon fillers are the various starches, such as cornstarch, 
rice fiour, arrowroot, wheat flour, eggs, an excess of 
gelatine and the like. 



52 THE BOOK OF ICE-CREAM 

40. Gelatine. — Commercial gelatine is an animal 
product made from bones, hides, skins, tendons, horn 
piths, tannery trimmings and any kind of connective 
tissue from the animal's body. Pure gelatine is an amor- 
phous, more or less transparent substance of vitreous 
appearance. It is brittle when dry, free from color, taste 
and smell. Gelatine and glue are manufactured from 
the same materials, more care being used in making 
gelatine. 

The detail process of making gelatine varies in the 
different factories, but the general steps are as follows: 
Treating and cleaning the raw material; dissolving gela- 
tine; concentrating; chilling and spreading; drying; 
finishing; including grinding and packing. Gelatine is 
put on the market in sheet, flake, shredded and powdered 
form. If made from clean materials, no objection can be 
raised against its use as a food. Gelatine swells in cold 
water, absorbing five to ten times its weight of water. 
This is sufficient water to dissolve it at a temperature of 
85° F. to 90° F. The strength or gelatinizing power of 
different samples of gelatine varies within wide limits. 
The following is a simple method to compare different 
gelatines: Take ten grams of the sample and soak over 
night in 100 cubic centimeters of cold water. The next 
morning dissolve the gelatine at a temperature of 80° C. 
First note the odor. It should not be pronounced or 
disagreeable. Determine length of time it takes for a 
50 cubic centimeter pipette full to run out. Note the 
time it takes to gelatinize. Test the strength with a 
jelly tester which is a simple arrangement to deter- 
mine the -weight necessary to force a plunger into the 
gelatine. 

41. Preparing gelatine for use in the ice-cream. — In 



SUGAR, CHOCOLATE PRODUCTS, ETC. 



53 



order to utilize gelatine in ice-cream, it must be brought 
into solution. A steam-jacketed copper kettle is usually 
employed for heating the gelatine (Fig. 7). If a smaller 
quantity is taken or a special gelatine cooker is not avail- 
able, a double boiler or a can set in water can be used. 
Whatever utensil is selected to cook the gelatine, it should 
be kept clean. In many ice-cream factories, the gelatine 
cooker is badly neglected. Before the gelatine is heated, 
it should be soaked 
in cold water. One 
pound of gelatine 
should be put into 
about eight quarts of 
water. Some prefer 
to use milk instead 
of water. The gela- 
tine should be stirred 
into the water rather 
than the water poured 
on to the gelatine. 
This will to a large 
extent eliminate the 
formation of lumps 
which would require 
excessive heating to 
break them down. 
The gelatine should be soaked from twenty to thirty min- 
utes in cold water before the heat is applied. This soaked 
or soft gelatine should then be placed in a water-jacketed 
heater and heated to a temperature of 165° F. to 170° F. 
In case the gelatine is soaked in milk, it should not be 
heated above 145° F. A higher temperature is very liable 
to give it a cooked or scorched 'flavor. At this lower tern- 




Fig. 7. — Steam-jacketed kettle for 
heating gelatine. 



54 THE BOOK OF ICE-CREAM 

perature, it is advisable to hold it ten or fifteen minuses to 
make sure that the gelatine is all broken down. It is nec- 
essary to heat the gelatine to the temperature mentioned 
above to secure the best results. The eye cannot deter- 
mine when the gelatine is all broken down. There is dan- 
ger of over-heating; it should not be held at high tempera- 
ture for long periods of time nor allowed to boil. In put- 
ting the gelatine into the mix, it should be done at the 
above mentioned temperatures for dissolving; not all at one 
time, but poured in slowly and with as rapid agitation of 
the mix as possible, and it will distribute itself more evenly 
before it has time to congeal. A good gelatine will jelly 
at a temperature of 85° to 90°, according to the pro- 
portions used; so that when pouring gelatine into a mix 
with a temperature probably of 45° or 50°, it is very 
liable to harden and make the ice-cream lumpy. 

42. Gum tragacanth. — This is a compound gum ob- 
tained from a shrub, a species of Astragalus. In July or 
August the leaves are stripped from the shrub and a hole 
made in the bark. The shape of the hole regulates the 
form of the gum, a longitudinal cut making the leaf or 
flake form, a puncture the thread form, and an irregular 
hole a knob-like mass. The gum is gathered by the 
natives. Dry weather gives a whitish colored gum which 
is best; wet and dusty weather give an inferior yellowish 
gum. 

Gum tragacanth will absorb fifty times its weight of 
water. For use in ice-cream, the gum is soaked in water, 
one ounce of gum absorbing two quarts of water. At 
least twenty-four hours should be allowed for this ab- 
sorption. Before being put in the ice-cream, the mixture 
should be strained to remove any lumps. If it is not all 
to be used as soon as soaked, a gum stock may be pre- 



SUGAR, CHOCOLATE PRODUCTS, ETC. 55 

pared by adding sugar at the rate of two pounds for each 
quart of water. This will act as a preservative. Gum 
tragacanth is odorless and tasteless. Just how it acts as 
a binder is not known. 

43. Other substances used as binders. — Two plants, 
Irish and Iceland moss, are sometimes used as binders. 
The former is a sort of algse and the latter a lichen. They 
are both very low in food value. 

44. Eggs. — In some kinds of ice-cream, eggs are neces- 
sary to give the characteristic body and texture. When 
eggs are employed, it is usually as a filler, since it is possi- 
ble to reduce the percentage of either the Inilk-fat or 
milk solids not fat or both. The usual practice is to 
separate the yolks and whites of the eggs. The yolks are 
cooked with the cream if used and the whites beaten and 
added just before the ice-cream is frozen. Eggs usually 
give ice-cream a smooth texture and a firm body. They 
also impart a characteristic flavor. 

45. Starchy fillers. — Several starchy substances, such 
as cornstarch, rice flour, arrowroot and wheat flour, are 
sometimes used in large quantities and so become fillers. 
They give a characteristic starchy flavor to the ice- 
cream. They are often employed to cheapen the prod- 
uct. The starches are ordinarily cooked before using 
but sometimes are mixed with the sugar and used with- 
out cooking. 

46. Prepared ice-cream powders.— A large number 
of prepared substances, both powders and liquids, is on 
the market. These are often used in the place of some 
other binder. They may contain any or all of the materi- 
als previously mentioned, and in addition they often 
contain sugar to give both bulk and weight. These 
powders are usually added to the ice-cream by mixing 



56 THE BOOK OF ICE-CREAM 

with the sugar. Many times, in proportion to the results 
obtained, they are found to be expensive. 

47. Rennet. — Another binder is some form of rennet. 
Its use is not common and is ordinarily in combination 
with other materials. 



CHAPTER V 
FLAVORING EXTRACTS* 

Because of the distinct taste which the flavoring ex- 
tract imparts to the ice-cream, it is important that it be 
of good quahty. The vanilla extract is most common, but 
lemon, orange, pistachio, almond, various fruit, and others 
are used to some extent. 

Flavoring extracts are prepared commonly by grinding 
or chopping the sources of their various flavors and steep- 
ing or dissolving them in alcohol; or by distilling them, 
wholly or fractionally; or, when necessary for any reason, 
simulating them by chemistry, or by the use of a flavor 
source to all intents the same as the original. 

VANILLA EXTEACT 

Extract of vanilla, properly made, is the pure essence 
of the vaniUa bean, dissolved in alcohol. 

Although there are fifty or more kinds of vanilla plant, 
the only one with a fruit suitable for use in flavoring 
extract is Vanilla planifolia, so called by botanists for 
its flat leaves. It is a native of the valley of Mazantla, 
in Vera Cruz, Mexico, seemingly the only place where 
conditions of soil and climate suffice to bring it to its 
highest point of cultivation. The other vanillas, native 
to various parts of Spanish America, are fit only for use 

* This article on flavoring extracts is furnished by the Joseph Bur- 
nett Extract Co., Boston, Mass. 

57 



58 THE BOOK OF ICE-CREAM 

in perfumery and soap, because, though aromatic, they 
are rank in taste. 

48. Nature of vanilla plant. — The plant of vanilla 
is an orchid, having roots in the air as well as in the 
ground. It clings to trees or frames, twining around 
them as it grows, and favors most a light, loose soil, well 
drained, with '^ quilted sunshine and leaf -shade," a con- 
dition naturally brought about by the foliage of the 
protecting trees. In Mexico it is grown from cuttings set 
out in the forest, one to a tree; this support, together 
with 70 to 90 degrees of continued heat, frequent rains, 
and a final dry season being needful to its best growth. 
Frost is deadly, and in too close planting disease is likely 
to ravage the crop. 

After eighteen months, the vine is clipped to check its 
growing until it bursts into flower, which occurs in Sep- 
tember. The stem of the vanilla is thick and round, the 
leaves large, smooth and pointed, the flower beautiful, 
much resembling the tuberose, and delightfully fragrant. 

Formerly the blossoms were fertilized by a small bee, 
which carried the pollen from one to another, for the 
plant is of two sexes. At present this is done by hand — a 
better way, inasmuch as only the best flowers need be 
fertilized, the plant thereby keeping vigorous and healthy. 
Artificial pollenizing developed from transplanting vanilla 
in the island of Reunion, where the crops originally failed 
for lack of insects to carry the pollen. 

Following each blossom comes a small pod, but most 
of these pods fall off. The remaining ones mature in 
about six weeks, growing in bunches of six to ten, and 
resembling bananas, being five to ten inches long, yellow 
green, and banana-like in shape. They are watery and 
tasteless, without the pleasant aroma of vanilla, the 



FLAVORING EXTRACTS 59 

well-known taste and smell of which must be brought 
out by curing. If left on the vine, they ripen slowly, but 
usually they are picked before they ripen, as otherwise 
they split in curing. When this happens they are known 
to the trade as "splits," and are considered undesirable 
on account of their full and heavy flavor. 

49. Curing vanilla beans. — After picking, the Maz- 
antla beans are transported to Papantla, the largest town 
in the valley, to be cured. The process is laborious, and 
although somewhat primitive, very simple. 

The beans are exposed on frames to the sun by day and 
by night are wrapped in blankets under cover. This 
continues, in fair weather, for about a month; then the 
beans are dried indoors for forty days more, until they 
turn a deep rich brown in color, and become delightful to 
the smell. If the weather is wet, they are moistened, 
blanketed, and heated in ovens, the heat being moderate 
and varied with the size of the beans; after which they 
are by turns exposed to the air and heat until cured. The 
sun drying is preferred, as it gives the beans better keep- 
ing quahties. Such is the process in effect, but in fact 
each bean is treated separately; for proper curing, to 
bring out the desired fine qualities of taste and smell, is 
of the utmost moment; and only native judgment, or the 
skill born of long handling, ever gives the real adroitness. 
Badly cured beans lack any stable taste or smell, and are 
likely to become moldy. Their use in trade is made 
possible, in this case, by scraping and chopping them up 
with poor and broken beans and those that fell early 
from the vines; then they are sold under the name of 
"Mexican cuts," chiefly to manufacturers of cheap ex- 
tracts. 

50. Marketing vanilla beans. — The long fine beans, 



60 THE BOOK OF ICE-CREAM 

resembling thin cigars, are molded, pulled, and' tied in 
bundles of 100 to 150, varying in length from six to 
eleven inches, and in weight from twelve to twenty-four 
ounces. The bundles are packed forty to a tin, and 
shipped four tins to a case in sweet-smelling cedar 
boxes. The entire Mexican output is consigned to the 
United States, where it brings from seven to ten dollars 
a pound. 

The Aztecs knew the properties of vanilla, and are 
said to have called the plant thilxochitl. They used the 
bean in making chocolate, through which it became 
familiar to their Spanish conquerors, and thus to Europe. 
The name vanilla is derived from the Spanish word vaina, 
meaning sheath or pod, and the suffix -ilia, little. The 
use of vanilla in chocolate was its only notable one for 
many years, although during that time great medical 
properties were claimed for it. It was not until the eight- 
eenth century that some person now unknown discovered 
its general utility for flavoring. 

51. Production of vanilla beans. — Vanilla cultivation 
in Mexico was in the hands of the Indians for centuries, 
but in 1896 the government, claiming they had no title, 
drove them off and sold the land to Greeks, who now 
control the industry there. 

Almost every European power has tried to grow vanilla 
in the tropics, outside of Mexico. Many of the early 
trials were failures; none has been a complete success, at 
least in so far as rivaling the fine quality of the Mexican 
product is concerned. Cuttings were transplanted in the 
island of Reunion and grown by artificial pollenizing, as 
has been^aid, but the resulting beans were not as good 
as the parent beans of Mexico. Reunion was formerly 
known as Bourbon Monarchy, but the French, who had 



FLAVORING EXTRACTS 61 

every reason to hate the name, rechristened the island; 
the beans, notwithstanding, are still called Bourbon 
beans. 

Vanilla grows in Reunion much as it does in Mexico, ex- 
cept that it takes longer to develop. The great difference 
is in the curing, for there, owing to the climate, the sun 
treatment is inexpedient. The beans, placed in baskets, 
are plunged into hot water for about twenty seconds, 
drawn out to drain for as many minutes, and then wrapped 
in blankets to be sunned during the warm hours for five 
to eight days. They are housed at night as in Mexico, 
but drying is also hastened chemically with chloride of 
calcium (the basis of lime). After curing, the beans are 
straightened, graded by size, smell, and soundness, 
bundled and packed in tins which weigh, when ready for 
export, from ten to twenty pounds each. 

Tahiti exports a particularly inferior quality of beans. 
They are grown from Mexican or Bourbon slips, but the 
change of soil and climate imbues them with an unmis- 
takable rankness, to which, up to within a few years, 
were added careless growing and packing, in nowise im- 
proving them. Although inspection by the French colo- 
nial government has somewhat bettered the care of these 
beans, their flavor is probably unchangeable. Tahiti 
beans are all shipped to the United States, whence those 
not used are reshipped to Europe. They are sorted here 
into three grades: pink label, best; white, fair; green, 
poor; but the only real difference is their length and 
appearance. 

A small crop of beans grown from Mexican slips is 
raised in the island of Guadeloupe; they are known to the 
trade as "South Americans," and are of low quality, 
without the finer characteristics of good vanilla. 



62 THE BOOK OF ICE-CREAM 

The average world's production of vanilla is as follows: 

Mexican: 

Whole beans .240,000 pounds 

Cuts 80,000 " 

Bourbon: 

(From aU sources) 700,000 " 

Tahiti ■ 450,000 " 

South American 25,000 " 



Total 1,495,000 



II 



52. The ingredients of vanilla extract. — Vanilla beans, 
glycerine, sugar and alcohol are the only ingredients 
requisite or advisable in a vanilla extract; consequently 
the excellence of such an extract rests in the quality of 
the beans and of the alcohol employed, and in the means 
and skill devoted to employing them. 

The process at its best is chopping or grinding the 
beans and treating them with dilute alcohol of 20 to 70 
per cent strength, in the proportion of one part of the 
bean to ten parts of the liquid, the alcohol acting as a 
solvent. The old-fashioned and as yet unequaled way 
is to treat the beans by steeping and dissolve out the 
soluble matter. The chopped beans are placed in a cask 
and the dilute alcohol poured over them; they are then 
left to soak for one to twelve weeks, when the extract is 
drawn off and the sugar added to it, and it is either bottled 
immediately or aged. Aging greatly improves it, but few 
manufacturers care to assume the added cost. 

Another method of obtaining the extract is by distilla- 
tion; that is, by evaporating and condensing the liquid 
in which the beans have been steeped. There is also a 
machine which effects the result more rapidly by pump- 
ing the liquid steadily through the chopped beans, at an 
even temperature. Many other means are also employed. 



FLAVORING EXTRACTS 63 

They are all cheaper than the old-fashioned way, but 
have nothing to recommend them from the consumer's 
point of view. Distillation, for example, might ruin the 
delicate flavor of choice Mexican beans; while no process 
would ever impart one to Bourbons or Tahitis. 

53. The chemistry of vanilla. — Given the highest 
grade of Mexican beans and pure cologne spirit — the 
trade name for doubly distilled alcohol — with the old- 
fashioned method of compounding them, and there re- 
mains to vanilla extract-making only the knowledge and 
skill available in the process. These, however, are far 
from comprising the whole secret of success. Although 
seemingly a matter of chemistry, extract-making has 
always been a stumbling-block to the chemist. Chemi- 
cally, there is no difference between the richest Mexican 
beans and the wretchedest Tahitis, but to even a normal 
nose the difference is striking and immediate. 

There is still much to be learned about the chemistry 
of vanilla. Its flavor is known to be due to natural vanil- 
lin, the chief flavoring principle of the plant, and to certain 
gums and resins, but of these last next to nothing is 
known. Yet if aptitude and experience still play the 
leading part in well-made extracts, chemistry without 
question takes the center of the stage in the adulterated 
ones. 

Under the present law (1913), an extract may be sold 
as "extract of pure vanilla" if it is made of genuine vanilla 
beans; consequently "Mexican cuts,'' "splits," and rank 
Tahitis can be and are sold under this label; whereas 
some extracts, though strictly speaking not adulterated, 
are really worse than some adulterated ones. These 
"cheap vanillas" are made possible by the difference in 
cost between fine Mexican beans and poor defective ones, 



64 THE BOOK OF ICE-CREAM 

or beans of other growth; a matter, as a rule, of four or 
five dollars a pound; and are readily exposed by a com- 
parative test in cookery or on the tongue. 

54. Adulteration of vanilla extract. — ^A common adul- 
terant of cheap vanillas is artificial coumarin. Real 
coumarin is an aromatic crystalline substance found in 
the Tonka bean or cumaru. Tonka beans were formerly 
rampant in imitation vanillas, but their present high 
price, due to their use in cheap tobacco, has practically 
curtailed this activity. The Tonka, with its real cou- 
marin, was bad enough — ^the theory has even advanced 
that hayfever is due to the presence in the air of coumarin 
from plants — but artificial coumarin, as flavoring, is 
worse. It is a powerful drug; a coal tar product, heart 
depressant and active poison. 

Artificial vanillin produced by chemistry also is em- 
ployed plentifully, not only in substitution but also for 
strengthening weak pure extracts. The real vanillin is 
one of the odorous principles of the vanilla bean, taking 
the form of tiny crystalline needles of hot bitter taste. 
It is imitated chemically by combining oxygen and 
eiigenol, a colorless compound from oil of cloves, of bay, 
of cinnamon leaves, or of allspice; or by coniferin, a com- 
pound ether obtained from wood. Lacking the necessary 
gums and resins, it does not taste like real vanilla, and 
needless to say, its composition is not such as to inspire 
confidence. 

Coumarin and vanillin are ordinarily used together in 
adulterating; the mixture is then sweetened and artificially 
colored, with prune juice added. This sometimes brings 
a substantial profit of 150 per cent to its manufacturer. 

Fortunately detection of these subterfuges by simple 
means is not difficult. A suspected extract can be tested 



FLAVORING EXTRACTS 65 

by holding a tablespoon of it over a lamp or other flame 
until about two-thirds of the liquid has evaporated; then, 
if on adding water to the remaining third until the spoon 
is full, the extract remains clear, undoubtedly it is not 
vanilla but an artificial product. Taste and smell, if one 
is familiar with true vanilla, are often test enough; cou- 
marin in particular can be recognized by its odor, which 
is like that of Indian grass or ''wood grass." 

The best test for the quality of vanilla is to pour a few 
drops on a lump of sugar, and then suck the extract 
through the lump. To determine the relative values of 
two or more extracts, a separate lump should be used for 
each. The distinction between good and bad will then 
be marked sharply. Finally, to avoid adulteirated ex- 
tracts, the label should be read carefully. 

LEMON AND ORANGE EXTRACTS 

Owing to its refreshing aroma, convenience in use, and 
low cost, lemon extract holds popular favor as second to 
vanilla. 

Extract of lemon is made by dissolving lemon oil, 
chiefly from skin of the fruit, in alcohol. To conform to 
the government standard, the compound must contain 
at least 5 per cent of the oil. 

The world's yearly yield of lemon oil is about two 
million pounds, of which southern Italy and Sicily pro- 
duce the most, although there is some output from France 
and Spain. The best is shipped from Messina. 

55. Preparation of lemon oil. — ^Lemon trees flower 
in the summer, and the fruit is picked from November to 
February. As the oil from the later fruit has the richer 
color, many makers prefer it, but the earlier oil has the 
finer flavor. 



66 THE BOOK OF ICE-CREAM 

Lemon oil is extracted most satisfactorily by washing 
and paring the lemon skin so that it comes off in one 
piece, and then pressing it against a clean sponge. The 
sponge absorbs the oil, and when full is squeezed into a 
container from which the oil is filtered and packed in 
sealed copper vessels, holding either ten or twenty-five 
pounds, for shipment. 

In France the fruit is sometimes rolled about in vessels 
driven full of spikes, the oil running into a receptacle 
below. Another method is to press the whole fruit in a 
large vat, add water, and distill the resulting mixture. 
This has been tried in California, although without suc- 
cess, since the oil thus secured is very bitter, tasting 
strongly of turpentine. 

56. The chemistry of lemon oil. — The oil is known 
to contain a large amount of terpenes or principles chem- 
ically hke turpentine, which would account for such a 
taste or smell in a poor or stale product. These, with 
6 to 10 per cent of citral, the chief flavor-giving constit- 
uent of lemon oil, would seem to identify the peculiar 
lemon taste; although there are certain unknown esters, 
or compound ethers, corresponding to the salts in met- 
als, which also are taken to be factors of it. Citral is 
found in exactly the same form in limes, mandarins, 
and oranges. 

Adulteration of lemon extract consists usually in either 
lowering the required amount of oil, or using in place of 
it citral, oil of lemon-grass, or some other natural oil 
containing citral. These substitutes naturally fail to 
give the true flavor, because they are lacking in terpenes, 
and presumably in the esters just mentioned. Many 
makers, to weaken the extract, lessen the alcohol; this 
indicates that their product cannot be made of lemon oil, 



FLAVORING EXTRACTS 67 

because this will not dissolve in dilute alcohol. In most 
cases, weakened extracts are made of citral. 

Terpenless lemon and orange extracts are made from 
lemon and orange oils from which the terpenes have been 
removed. They are much in favor among makers of low- 
grade flavors because they are soluble in very weak alco- 
hol, and because considerably less oil is needed to make 
the extract. On account of the removal of the terpenes, 
the flavor is of course quite different from that of the true 
oils. 

Using stale lemon oil in extract is not against the law, 
but no one is likely to buy more than once a product so 
compounded, for its foul taste of turpentine will ruin any 
cooking in which the extract is used. 

To test lemon extract a little should be poured from the 
bottle, the cork replaced, and the bottle shaken for a few 
seconds. If the bubbles disappear at once, there is no 
water in the extract, and it is probably pure. If they 
disappear slowly, there is water in it, and the extract can 
contain no lemon oil. Or a teaspoonful of the extract 
may be added to a glass of water; if small drops of oil 
come to the surface, and the water, on standing, becomes 
cloudy, the extract is probably pure. But if the extract 
dissolves immediately, leaving the water clear, it is not 
pure, and contains no lemon oil. 

No adulterated extract of any kind is really cheap. It 
is an actual fact that in a test of an adulterated lemon 
extract against a pure one costing twice as much, the 
pure one at but double the cost was found to be ten times 
as strong, in addition, of course, to its having by far the 
better flavor. 

57. Orange extract. — Like lemon, orange extract must 
contain at least 5 per cent of the fruit oil. The only 



68 THE BOOK OF ICE-CREAM 

chemical difference between orange and lemon oil is that 
the former has an infinitely small proportion of flavoring 
esters not found in lemon. The two fruits are grown in 
the same countries and in the same way, the methods of 
producing the two oils are identical, and the tests for the 
adulteration of the one extract hold good for the other. 

58. Fruit extracts. — Raspberry, strawberry, cherry, 
apple, pineapple, banana, and other familiar fruit flavors 
constitute a class of flavoring extracts similar in character 
and similarly made. They can be derived from their 
respective fruits, although previous to 1911 this was 
thought impossible. Up to that time, imitation extracts 
had been compounded chemically from coal tar ethers and 
esters, and ether was added often to give them pungency. 
They all tasted alike and none of them tasted like any 
fruit. One difficulty in making real fruit extracts was 
the lack of the essential oils in the several fruits; another, 
the change brought about in the delicate esters, the cause 
of the flavor, by cooking, since great heat destroys them. 
Pure fruit extracts are in every way immeasurably su- 
perior to the old unwholesome and unhealthful ether 
preparations, of which purchasers should beware. Fruit 
flavors labeled artificial or imitation are of the type; if 
not labeled, they can be detected by the odor of ether 
rising when the cork is drawn. 



CHAPTER VI 
CLASSIFICATION OF ICE-CREAMS 

Because of the large variety of materials used and the 
different methods of blending and preparing them, it is 
desirable to have a classification of ice-creams. Several * 
classifications have been made but the following, based on 
the materials used and the method of preparing them, 
seems best adapted for general use. These classifications 
have been based on the materials employed, the flavoring 
materials used, and the form in which the ice-cream was 
put up for market. 

59. Classification of ice-cream. — The following is 
based on the materials used; the subclasses are divided 
according to the flavoring materials. 

I. Plain ice-cream, often known as Philadelphia ice- 
cream, is made from cream, sugar, and flavoring, with or 
without condensed milk or some stabilizer. This class 
may be subdivided as follows: 

(1) Plain — flavors are used such as vanilla, chocolate, 
caramel, coffee, mint, maple. 

(2) Fruit — afresh or canned fruits are employed for 
flavors, such as peaches, strawberries, cherries, pine- 
apples, raspberries. 

* Mortensen, M., '' Classification of ice cream and related frozen 
products," la. Exp. Sta., Bui. 123, 1911; Washburn, R. M., "Prin- 
ciples and practice of ice cream making," Vt. Exp. Sta., Bui. 155, 
1910; Frandsen, J. H., and Markham, E. A., " The manufacture 
of ice cream and ices," Orange Judd Co., 1915. 

69 



70 THE BOOK OF ICE-CREAM 

(3) Nut — nuts such as walnuts, almonds, chestnuts, 
pistachio, furnish the flavoring. 

(4) Bisque — ^materials are used for flavoring such as 
macaroons, marshmallows, grapenuts, sponge cake. 

(5) Mousse — ^rich whipped cream sweetened and flavor 
folded in, sometimes eggs are used. 

II. Cooked ice-cream, often known as French or Nea- 
politan, is made from cream, sugar, eggs, and flavoring. 
As custards they sometimes contain flour or cornstarch. 
This class may be subdivided as follows: 

(1) Parfaits or French — flavors such as vanilla, choco- 
late, and the like are the most common but various fruits 
are sometimes used. 

(2) Puddings — these are highly flavored with various 
dried and candied fruits, nuts, and spices and eggs. 

(3) Custards — these contain flour, cornstarch, or other 
similar ingredients and are almost always flavored with 
vanilla. 

III. Sherbets and ices are made from water or milk, 
sugar, often egg albumen and a stabilizer, and flavored 
with fruit juices or other natural flavorings. 

(1) Ices — ^made'from water, sugar, and some natural fla- 
voring without eggs or a stabilizer. This may include gran- 
ites and frappes. Granites are frozen with little agitation, 
while frappes are only semi-frozen to a slushy consistency. 

(2) Water sherbets — ^made the same as ices with the 
addition of egg-whites and sometimes a stabilizer. If the 
whole egg is used, they are sometimes called souffles. 

(3) Punches— ices or water sherbets flavored with 
liquors or highly flavored with fruit juices and spices. 

(4) Milk sherbet — ^made from whole or skimmed- 
milk, sugar, and egg-whites, with or without a stabilizer 
and flavored with some natural flavoring. 



CLASSIFICATION OF ICE-CREAMS 71 

(5) Lacto *^ — made from skimmed or whole sour milk 
instead of sweet milk but in other respects resembhng 
milk sherbets. 

60. Receipts for ice-cream. — ^A large number of receipts 
or formulas for ice-cream might be given. Each manu- 
facturer usually has a receipt for his own use, which is 
slightly different from any other. Ordinarily ice-cream 
manufacterers employ the same classes of materials but 
in different amounts. The receipts given are typical of 
those used and give satisfactory results. So far as possible 
receipts will be given which use the various materials and 
at the same time vary the composition. 

61. Vanilla ice-cream. — These receipts may be used 
as a basis for other ice-creams by substituting other 
flavors. These provide a basis for all plain ice-creams. 

Receipt No. 1. 

40 lbs. 20 per cent cream 
9 " sugar 

4 oz. gelatine dissolved in 4 lbs. water 
4 " vanilla 

Receipt No. 2. 

32 lbs. 20 per cent cream 

8 " whole or skimmed-milk condensed 

9 " sugar 

4 oz. gelatine dissolved in 4 pounds of water 
4 " vanilla 

Receipt No. 3. 

26 lbs. 18 per cent cream 

14 " skimmed-milk condensed 

8 " sugar 

4 oz. gelatine dissolved in 4 pounds water 

4 " vanilla 

* Mortensen, M., " Lacto, a frozen dainty product," la. Exp. Sta., 
Bui. 140, 1913. 



72 THE BOOK OF ICE-CREAM 

Receipt No. 1 will test from 14-15 per cent of fat. 
Receipt No. 2 will test 13-14 per cent fat if whole milk 
condensed is used and 11-12 per cent of fat if skimmed- 
milk condensed. Receipt No. 3 will test 8-9 per cent of 
fat. 

62. Chocolate ice-cream. — Either chocolate or cocoa 
may be employed to give the chocolate flavor. Some 
manufacturers prefer one and some the other. A thick 
chocolate sirup may be purchased from some flavor 
manufacturing concerns. A pound to a pound and a 
quarter of chocolate or cocoa is sufficient for a ten-gallon 
mix. The chocolate or cocoa may be softened in either 
water or milk. The cocoa forms a liquid much easier. 
The best way to prepare either is to put it into a double 
boiler and cook until a thick sirup is formed. About two 
quarts of milk or water is sufficient for a pound or a pound 
and a quarter of chocolate or cocoa. This can be used 
with the mixes given for vanilla ice-cream. Some manu- 
facturers of ice-cream prefer some vanilla with the choco- 
late, believing that it imparts a better flavor. 

63. Caramel ice-cream. — This may be made by sub- 
stituting caramel flavor for the vanilla in each receipt. 
The flavor may be obtained by caramelizing or carefully 
burning sugar or by adding prepared caramel flavor. The 
amount of either which should be used depends on the 
strength of the flavor. 

64. Coffee ice-cream. — Ice-cream may be flavored by 
the addition of coffee. The amount to use will depend 
on its strength. The coffee should be strained and only 
the liquid portion added. It may be substituted for the 
vanilla in the receipts. 

65. Maple ice-cream. — Maple sirups or prepared 
maple flavor may be used to flavor ice-cream in place of 



CLASSIFICATION OF ICE-CREAMS 73 

the vanilla. The amount depends on the strength of the 
materials used. 

66. Fruit ice-cream. — Various flavors of fruit ice- 
cream may be made by substituting the fruit for the 
vanilla in the receipts already given. Either the fresh 
fruit or the preserved or canned ones may be used. In 
many cases the fruit sirups or extracts are employed 
either alone or with the fruits. It is usually customary to 
add a small amount of color to mix with the fruit in order 
to give the product the characteristic fruit color. This 
is not necessary but adds to the appearance of the ice- 
cream. The amount of fruit necessary depends on its 
flavor; for example, fruits with a very pronounced flavor, 
such as raspberry will go further than a fruit with a very 
delicate flavor such as peach. Usually two quarts of 
preserved fruits are enough to make ten gallons of ice- 
cream. The fruit should be chopped before adding. 

67. Nut ice-cream. — Various nuts maj^ be employed 
to flavor ice-cream but they are not commonly used 
alone. The most common is pistachio. In this case the 
nut itself is not utilized ordinarily but an imitation flavor, 
and the ice-cream colored green. This is a trade custom. 

68. Bisque ice-cream. — Various bread products may 
be used to flavor ice-cream, the result being called bisque. 
The common material is macaroons, but other materials 
such as sponge cake, grape nuts, and dried cakes may be 
added. The material should be dried and then ground 
through a food chopper before it is added to the ice- 
cream. 

69. Mousse. — This differs from the other plain ice- 
creams as the cream is whipped first and the flavoring 
then folded inside. Various flavors may be used, but 
maple is the most common. 



74 THE BOOK OF ICE-CREAM 

Mousse foundation 

4 eggs 
20 egg -yolks 

1 lb. sugar 

2 qts. whipped cream 

Cook sugar to heavy thread. Beat the eggs and yolks 
and pour sugar in slowly. Beat on ice until cold. Add 
whipped cream, mixing thoroughly. Fruits and nuts may 
be added. 

70. Cooked ice-cream. — No basic receipts can be given 
for Class II as for Class I, in which the various flavoring 
materials may be substituted. Most of the cook-books 
give numerous receipts which belong to this class. In 
fact there are so many receipts for cooked ice-creams 
that only a few of the better ones can be given; they are 
usually made in small quantities. 

71. Parfait. — The use of eggs makes an ice-cream 
of different flavor and body. This is the main difference 
between parfait and the plain ice-creams in Class I. Usu- 
ally the eggs are cooked either in afl or a part of the mix 
before they are added to the freezer. 

Receipt No. 1. 

40 lbs. 20 per cent cream 
10 " sugar 

4 oz. vanilla 

8 doz. eggs well beaten 

Beat the egg-yolks till smooth, add the sugar, and beat 
again till it is dissolved. Beat the whites to a stiff froth 
and stir into the yolks and sugar. Mix all with the cream 
and cook in a double boiler to a temperature of 180° F. 
for fifteen minutes. Cool to 40° F., add vanilla and 
freeze. 



CLASSIFICATION OF ICE-CREAMS 75 

Receipt No, 2. 

40 lbs. 28 per cent cream 
10 " sugar 

4 oz. vanilla 

8 doz. eggs well beaten 

2 qts. crushed strawberries 

Beat whole eggs together, add to the mix and freeze, 
or the whites may be beaten separately if desired and 
added after the mix is partly frozen. 

Receipt No. 3. 

40 lbs. 25 per cent cream 
12 " sugar 

4 oz. vanilla 

4 lbs. chopped walnut meats 
yolks of 8 dozen eggs 

Beat the egg-yolks till smooth, add the sugar and beat 
again. Then add to the cream and cook in a double 
boiler to 180° F. for fifteen minutes. Cool, add the bal- 
ance of the mix, and freeze. 

Other nuts or fruits may be substituted for those 
mentioned in the above receipts. 

72. Puddings. — This product is usually very rich and 
is a combination of cream, sugar, eggs, spices, various 
fruits and nuts. 

Receipt No. 1. — Nesselrode 

32 lbs. 28 per cent cream 
10 doz. eggs 
10 lbs. sugar 

6 oz. vanilla 

4 lb. chopped walnut meats 

3 " " candied cherries 

3 " " " fruits 

4 " " raisins 

Cook the egg-yolks with the cream. Beat the whites 
and add when partly frozen. 



76 THE BOOK OF ICE-CREAM 

Receipt No. 2— English Plum 

32 lbs. 25 per cent cream 

8 doz. eggs 
12 lbs. sugar 

3 " cocoa or chocolate 

5 " assorted fruits that do not pulp 

2 " seeded raisins 

3 " dates 

4 '' walnut meats 

4 tablepoonfuls ground cinnamon 
1 '' ginger 

1 " ground cloves 

Use the eggs as directed under receipt No. 1. Chop 
the fruits and nuts fine. ' 

Receipt No. 3 — Fruit Pudding 

32 lbs. 10 per cent cream 
8 " whole condensed milk 
8 " sugar 

5 oz. gelatine dissolved in part of cream 

2 lbs. chopped cherries 
2 " " raisins 

2 " " nuts 
1}4. qts. sherry wine 

Soak the fruit overnight in sherry wine. 

Receipt No. 4 — Manhattan Pudding * 

3 gals. 30 per cent cream 
10 doz. eggs 

12 lbs. sugar 
2 qts. orange juice 
1 pt. lemon juice 

4 lbs. walnut meats 
4 " pecan meats 

4 " cherries and assorted fruits 

73. Custards. — A custard is usually made of milk, 
sugar, flavoring, cornstarch or flour and the process is 

* la. Bui. No. 123. 



CLASSIFICATION OF ICE-CREAMS 77 

rather long. Quantities given in receipts are for hand 
freezers. 

Receipt No. 1. 

6 qts. milk 

3 lbs. sugar 
24 eggs 
12 tablespoonfuls cornstarch 

6 " vanilla or to taste 

Put the milk over the fire in a farina or double water i 

boiler. Moisten the cornstarch with a little cold milk so 
that it can be added to milk without lumping. When the - 
milk is hot, add the cornstarch and stir until it begins to 
thicken. Beat the eggs and sugar together until light and i 

then add them to the hot milk. Cook a few minutes, 
take from the fire, flavor and cool ^and freeze same as 
ice-cream. 

Other flavors, as coffee or chocolate, may be made by 
substituting these flavors for the vanilla. 

Receipt No. 2. 

5 qts. milk 

1 qt. 30 per cent cream 
8 eggs 

23^2 lbs. sugar 

6 tablespoonfuls flour 
13^ oz. of vanilla to taste 
Follow directions given for No. 1 

Receipt No. 3. 

2 qts. 30 per cent cream 
4 " milk 

3 lbs. sugar 

13^2 qts. minute tapioca 
Yolks of 4 eggs 

1 teaspoonful salt 

4 teaspoonfuls lemon extract 

2 teaspoonfuls rose extract 



78 THE BOOK OF ICE-CREAM 

Cook the tapioca in 2 quarts of milk for ten minutes, 
then add the remainder of the milk, the sugar and the 
salt. Cook ten minutes longer. Remove from the fire 
and add the egg-yolks well beaten. Then add the extract, 
cool and freeze. When nearly done add the cream previ- 
ously beaten to stiff froth and finish freezing. A large 
number of receipts for custard ice-cream may be found 
in the various cook-books. 

74. Ices and sherbets are usually made either of water 
or milk, with or without eggs and flavoring. Some kinds 
are frozen without agitation and some beaten like ice- 
cream while freezing. 

75. Ices are simply water sweetened, flavored and 
frozen. They become grainy in texture very quickly. 

Receipt No. 1. 

48 lbs. water 
20 " sugar 
6 '' lemon juice 

Receipt No. 2. 

48 lbs. water 
20 " sugar 

2 " lemon juice 

4 qts. pineapple juice 

Receipt No. 3. 
48 lbs. water 
20 " sugar 

2 " lemon juice 

4 qts. finely pulped strawberries . 

76. Water sherbet. — The only difference between 
water sherbet and ices is that eggs are used in the former 
and not in the latter. 



CLASSIFICATION OF ICE-CREAMS 79 

Receipt No. 1. 

48 lbs. water 
16 " sugar 

1 lb. lemon juice 

4 qts. grated pineapple (or pineapple juice) 

6 oz. gelatine in 4 lbs. water, if desired 
24 egg-whites beaten stiff and added when mixture is 
partly frozen 

Receipt No. 2. Same as No. 1 except replace the pine- 
apple with grape juice. 

Receipt No. 3. Use same mix as No. 1 except replace 
the pineapple with orange juice. Boil the water and sugar 
to a clear sirup, then strain and cool before freezing. 

77. Punches. — The essential difference between ices, 
water sherbets and punches, is the material used for 
flavoring. 

Receipt No. 1. 

48 lbs. water 
20 lbs. sugar 

1 " lemon juice 

1 qt. brandy and rum mixed 

Receipt No. 2. 

48 lbs. water 
20 " sugar 
1 lb. lemon juice 

1 qt. orange juice 

2 qts. wine 

4 oz. gelatin in part of water 

Receipt No. 3. 

48 lbs. water 
20 " sugar 

1 qt. lemon juice 

1 " raspberry juice 

1 " grape juice 

cloves, cinnamon, allspice, and nutmeg to taste 



80 THE BOOK OF ICE-CREAM 

78. Milk sherbets. — These are similar to water sher- 
bets except milk is used in place of water. 

Receipt : 

48 lbs. milk 
16 " sugar 
5 ozs. gelatine in 2 qts. water 

1 lb. lemon juice 

4 qts. fruit flavoring 

12 egg-whites beaten stiff and added after mixture is 
partly frozen 

Flavors: Orange, grape, cherry, pineapple, and straw- 
berry. If lemon is desired, use only 2 quarts of lemon 
juice with 1 quart of orange juice. 

79. Lacto *. — This is the only receipt in which sour 
milk is used. 

Receipt : 

48 lbs. good starter just nicely coagulated 

18 " sugar 

24 eggs, whites and yolks beaten separately 

2 qts. grape juice 
l}/2 qts. lemon juice 

Mix in the order given in the formula. Other flavors 
may be substituted for the grape juice. 

*Ia. Exp. Sta. Bui. No. 140. 



CHAPTER VII 
EQUIPMENT 

The size and kind of equipment will depend on the 
extent of the business and the available capital. It is not 
considered economical to install a mechanical refrigerating 
system unless at least seventy-five gallons of ice-cream 
are manufactured a day. 

Certain factors should be considered when purchasing 
machinery; the construction and adaptability of the 
machine for the type of work it is intended to do; the 
ease of making repairs; the ease of cleaning; the durability 
of the machine; the protection to gearing from ice and 
salt. 

80. Freezers. — The general principle of the ice-cream 
freezer is the same in all makes; however, the application 
may be varied. The unfrozen ice-cream or mix is placed 
in a container, usually called the freezing-can. This can 
is surrounded by the freezing material, either cold circu- 
lating brine or an ice and salt mixture. In the can is the 
beater or dasher. To this is attached two scrapers which, 
when rotated, scrape the frozen ice-cream from the sides. 
The can itself may revolve or stand still, depending on 
the type of freezer. The dasher may revolve or stand 
still, depending on whether the can revolves or stands 
still. In most freezers there is another part of the dasher 
which revolves to help beat up the ice-cream. The 
freezers may be divided into two general classes. The 

81 



82 



THE BOOK OF ICE-CREAM 




Fig 



Fig. 8. — Hand freezer with tub and can 
cut away showing ice and salt mix- 
ture and beaters and scrapers in the 
can. 



9. — Hand freezer 
with fly wheel, using 
salt and ice mixture 
for freezing. The ca- 
pacity is five gallons. 




Fig. 10. — Power driven tub and can freezer, using a salt and ice 
mixture. The can, dasher, cover and gears are shown removed. 



EQUIPMENT 



83 



one class consists of a tub and can in which an ice and 
salt mixture is used between the tub and can. This type 
of freezer is made to run by hand or mechanical power, 




Fig. 11. — Horizontal brine freezer attached to salt and ice brine 
box. The pump is behind the box. 

and varies in size from a few pints to ten gallons. The 
largest hand size is usually five gallons; these have a 
flywheel. The types of hand freezers are shown in Figs. 
8 and 9. A power-driven tub and can freezer, using a 



84 



THE BOOK OF ICE-CREAM 



salt and ice mixture in the tub for freezing, is shown in 
Fig. 10. The other class is the brine freezer. In this, 
cold brine is forced around the freezing-can. The freezer 







Fig. 12. — Vertical belt driven brine freezer connected to ice and salt 
brine box. Pump is shown between freezer and box. 

runs by mechanical power, either belt-driven or directly 
connected to an electric motor. The brine may be made 
from an ice and salt mixture, or it may be cooled by an 
artificial refrigerating system. There are two general 
types of brine freezers. One has the freezer in a horizontal 



EQUIPMENT 



85 



position and the other in a vertical. Advantages are 
claimed for both. The arrangement of brine freezers 
when the brine is obtained from a salt and ice mixture is 
shown in Figs. 11 and 12. The brine as it comes from the 
freezer is sprayed over the ice and as it trickles through 




Fig. 13. — ^Perfection brine freezer, direct motor drive. 



is cooled again. It is then pumped around the freezer 
again. The ice is held in the box by means of a heavy 
wire screen; otherwise, it would clog the pump. 

Some of the types of brine freezers in common use are 
shown in Figs. 13, 14, 15, and 16. Most of these may be 
either belt or direct motor-driven. The usual size is ten 
gallons. In some cases they have been made larger but 



86 



THE BOOK OF ICE-CREAM 



these are not in common use. It is the usual practice to 
have a supply tank just above the freezer-can which can 




Fig. 14. — Progress vertical belt drive brine freezer. 

be filled, while one can is freezing. The mix for the next 
freezer is placed in this supply can and will then run 
quickly from it into the freezer. 

Another brine freezer is the disc which may be used 



EQUIPMENT 



87 



either as a batch or continuous freezer. A front view of 
this is shown in Fig. 17. The supply can is seen on one 




Fig. 15. — Emery Thompson vertical direct motor drive brine freezer. 



side and the delivery spout on the other. A glass plate 
over the freezing discs allows the process to be seen at 



88 THE BOOK OF ICE-CREAM 

any time. A side view is seen in Fig. 18, showing the 
brine box and pump. The freezing discs are illustrated 
in Fig. 19, also the scrapers to remove the ice-cream 




Fig. 16. — Fort Atkinson horizontal belt drive brine freezer. 



from the discs and the screw to force the ice-cream along. 
When used as a batch freezer, the ice-cream is drawn 
from the bottom. 

81. Mixers. — When large quantities of ice-cream are 



EQUIPMENT 



89 




■:^%4KJS(l(l!r^^l^$«ib,,,,_ 




Fig. 17. — Disc brine freezer either continuous or batch. 




Fig. 18. — Side view of 
freezer shown in Fig. 17. 
Arrangement of brine 
tank and pump are 
shown. 



90 



THE BOOK OF ICE-CREAM 



made, a container of some sort, with a mechanical agitator 
to stir the contents, is used to mix the ice-cream ingredi- 




FiG, 19. — Freezing discs of freezer shown in Figs. 17 and 18. The 
scrapers for removing the ice-cream from the discs and the 
screw to force it out of the delivery spout are shown. 

ents. Some of these mixers are provided with coils in 
which water or brine may be circulated to control the 




Fig. 20. — A pasteurizer or ripener used as an ice-cream mixer. 
Strips are attached to the coils to prevent the settling of the 
sugar on the bottom. 



temperature. Some may be operated as a pasteurizer. 
An ordinary cream ripener might be used as a mixer if 
the sugar could be prevented from settling to the 



EQUIPMENT 



91 




bottom. Some manufacturers have accomplished this 
by placing a strip of iron on the coils which will reach 
almost to the bottom of the ripener. Such an arrange- 
ment is shown in Fig. 20. An ordinary starter can 
might be utiHzed as a mixing vat or can. (Fig. 21.) 

A number of ice-cream mixers are 
conmionly used, as shown in Figs. 22, 
23, and 24. Most of these have 
coils which carry cold water or brine 
to cool the mix. In some these 
coils act as the agitator and in 
others they are placed in a jacket 
around the mixer. In order to keep 
the materials properly mixed if the 
coils themselves do not serve as the 
agitator, there is some form of me- 
chanical agitator. These agitators 
may be belt or direct motor-driven. 

82. Gelatine kettles. — In most 
plants where much ice-cream is made, 

a special kettle is employed to dissolve the gelatine. 
(Fig. 7.) This consists of a copper steam-jacketed ket- 
tle. With this the gelatine and water may be heated 
without danger of burning. The size of these kettles 
depends on the amount of gelatine used. 

83. Hardening the ice-cream. — Some means of keep- 
ing the ice-cream cold after it is removed from the freezer 
must be provided. This may be a specially cooled room 
known as a hardening room or the ice-cream may be 
packed in a mixture of salt and ice. These methods of 
hardening will be discussed later. 

84. Packing-cans. — In order that the freezer may be 
kept in use, as soon as the ice-cream is sufficiently frozen. 



Fig. 21. — Minnetonna 
starter can or ice- 
cream mixer. 



92 



THE BOOK OF ICE-CREAM 




Fig. 22. — Alaska ice-cream mixer. The side is cut away showing 
the coils and insulation. The mechanical agitator is seen at the 
bottom. By means of the tight fitting cover and the air pump, 
the mix may be forced to the freezer by air pressure. 




Fig. 23. — Wizard ice-cream mixer. 



Fig. 24. — Emery Thompson ice- 
cream mixer. 



EQUIPMENT 



93 



it is removed and placed in other cans to harden. These 
are known as packing-cans (Fig. 25) and are made of 
heavy iron and tinned and fitted with a cover. The cans 
vary in size from one quart to 
five gallons and the ice-cream 
is hardened and delivered in 
these. When ready for de- 
livery, these pack-cans are 
placed in tubs which should 
be a little higher than the 
pack-can to allow for ice over 
the top. There should be a 
space also of 2-4 inches be- 
tween the sides of the can and 
the tub to allow for the ice 
and salt. The ice-cream may 
be packed in small oblong con- 




ice- 



tainers known as bricks, usually ^^" ' ^°i .-^^^^ ° 

. cream packmg-cans, 

containing one or two pints. 

The ice-cream may be hardened in a larger brick mold 
which will make several smaller bricks. When hard the 
ice-cream is cut into the smaller bricks, wrapped in parch- 
ment paper and placed in a paper carton. This is the 
usual method of handling brick ice-cream. Several dif- 
ferent layers may be placed in each brick. 

85. Ice crushers. — The ice must be broken into small 
pieces for freezing or packing the ice-cream. This may 
be done by hand with an ice spud or cracker. (Figs. 26 
and 27.) If much ice is to be cracked or crushed, a me- 
chanical crusher should be used. (Fig. 29.) The small 
ones run by hand power but turn rather hard. The 
crushers run by mechanical power are more frequently 
seen in ice-cream plants. These vary in size. 



94 



THE BOOK OF ICE-CREAM 

I 






Fig. 26.— Ice 
spud. 



Fig. 27. — Ice cracker. 



Fig. 28.— Perforated 
ice shovel. 




Fig. 29. — Ice crusher with 
tight and loose pulley 
for mechanical power. 
The teeth or picks 
on the drum may be 
seen. 



Fig. 30. — The perfection 
ice-cream can-washer 
and sterilizer. 




EQUIPMENT 



95 




Fig. 31. — Fort Atkinson ice-cream can- 
washer and sterilizer. 



86. Ice-cream can-washers. — The washing of the ice- 
cream pack-cans by hand in an ordinary sink consumes 
much time. In the 
larger plants an ice- 
cream can-washer is 
used. This consists 
of sprays of water 
and revolving brushes. 
The cans are usually 
brushed both on the 
inside and outside. 
Some types of ice-cream can-washers and sterilizers are 

shown in Figs. 30 and 
31. When washed, 
the cans should be 
sterihzed. 

87. Emulsors, 
creamers, and homo- 
genizers. — These ma- 
chines vary consider- 
ably in mechanical 
construction as shown 
in Figs. 32, 33, 34, 35, 
and 36. Neverthe- 
less, the making of 
cream from butter, 
milk powder, con- 
densed milk or skim- 
milk is accomplished 
by each machine. The 
force used to break up 
Fig. 32.-De Laval centrifugal emulsor. ^^^ ^^^ ^^e materials 

varies with the different machines. One type which uses 




96 



THE BOOK OF ICE-CREAM 



steam as the force to break up the material is illustrated 
by Fig. 33. The amount of steam pressure required varies 




Fig. 33. — Perfection cream-maker and emulsifier. 



with the different makes. Another type of machine 
which uses centrifugal force as the means of breaking up 



EQUIPMENT 



97 



the materials is illustrated by Figs. 32 and 36. In this 
type, the materials are broken up or mixed by being 
thrown by centrifugal force through a very small opening 
or narrow space. The other type of machine, which is 
operated by valve pumps, is illustrated in Figs. 34 and 
35. By means of the pumps the materials are forced 
through a very small opening against some hard material. 




Fig. 34. — Progress homogenizer. 

This machine, known as a homogenizer, breaks the ma- 
terials into very small particles; for example, cream that 
has been homogenized cannot be re-churned in butter 
because of this. A good quality of cream may be made 
from any of the following combinations according to the 
DeLaval Separator Company: 

Skim-milk powder — water — butter — (preferably un- 
colored and unsalted). 

Whole-milk powder — ^water — butter. 

Condensed skim-milk — water — butter. 



98 



THE BOOK OF ICE-CREAM 



Condensed whole milk — ^water — butter. 
Skim-milk — skim-milk powder — butter. 
Skim-milk — condensed skim-milk — butter. 
Whole milk — skim-milk powder — butter. 
Whole milk — condensed skim-milk — butter. 




Fig. 35. — Gaulin homogenizer. 



One should never lose sight of the fact that the better 
the quality of the materials used, the better will be the 
flavor of the cream. It is impossible to make first-quality 
cream from poor materials. The whole milk and skim- 
milk must be clean and sweet. Skim-milk powder should 
be dry, loose, and fluffy. The condensed milk should be 



EQUIPMENT 



99 



clean flavored and fresh. Off-flavored condensed milk or 
milk that is grainy or gritty should never be used. The 
manufacturers of the various machines send specific 
directions for their operation. To insure success, these 
directions should be followed carefully. It is the usual 
practice first to put the milk 
powder into solution, then to cut 
the butter into small pieces and 
put it into the milk. If skim- 
milk is used, the butter is put 
directly into it. The milk and 
butter are then heated to a tem- 
perature high enough to melt 
the butter, usually 130° to 150° F. 
It is then run into the machine. 
Because of the tendency of the 
butter to rise to the top, the ma- 
terials must be kept in constant 
agitation until run into the ma- 
chine. Otherwise, the butter 
would be at the top and would 
not run into the machine until 
the other materials had all run 
through. 

Some makers emulsify or 
homogenize the whole ice-cream" 
mJxT' Tn tEis~"case,"~the flavoring extracts and fruits 
are not added until after the mix has been through the 
machine. It^is the general opinion that the emulsifying 
or homogenizing of the whole mix makes a smoother 
body and texture in the product. 

Advantages in the use of emulsors and homogenizers: 
1. Smoother body in ice-cream. 




Fig. 36. — Sharpies centrif- 
ugal emulsor. 



100 THE BOOK OF ICE-CREAM 

2. Less time required for ageing cream, especially 

pasteurized. 

3. Not necessary to carry so large a stock of raw 

materials. 

4. Ice-cream of more uniform composition. 
Disadvantages in the use of emulsors and homogenizers: 

1. The disadvantage in the use of the homogenizer 

is in its abuse since a homogenized cream will 
appear richer than it really is. There is a 
tendency to use less solids, especially fat. 

2. Danger of using inferior materials. 

3. If cream is not needed for ice-cream and has been 

homogenized, it cannot be churned. 
88. Cost of equipment. — Because of the constant 
change in price, it is impossible to give even estimates of 
cost of equipment. The price might be correct to-day 
and incorrect to-morrow. The cost of equipment based 
on the gallonage of ice-cream is usually higher for the 
smaller plant. In order to obtain accurate prices, the 
various dairy supply houses should be consulted. 



CHAPTER VIII 

REFRIGERATION AS APPLIED TO ICE-CREAM- 
MAKING 

In the making of ice-cream, refrigeration is necessary. 
In the following discussion only the underlying principles 
as apphed to operation will be taken up. The details of 
construction are discussed by refrigerating engineers in 
various text-books.* 

Refrigeration is the interchange of heat units. The 
cooUng for ice-cream-making may be obtained either 
from natural ice or from mechanical refrigerating ma- 
chines. These will be discussed under their separate heads. 

89. Terms used. — In order easily to comprehend 
the principles of refrigeration, it is necessary to under- 
stand the terms used.f 

''British thermal unit.— A British thermal unit 
(B. T. U.) is the quantity of heat required to raise 1 
pound of pure water 1 degree Fahrenheit, at or near its 
maximum density, 39.1° F. Some authorities consider 
a British thermal unit as the heat required to raise 1 
pound of pure water from 61° to 62° F. For practical 
purposes, however, it may be considered the heat required 
to raise the temperature of 1 pound of water 1 degree 
Fahrenheit. 

*Audels, "Answers on refrigeration," 700 pages; Cooper, Madi- 
son, " Practical cold storage," 800 pages. 

t Bowen, John T., *' The application of refrigeration to the hand- 
ling of milk," U. S. Dept. Agr. B. A. I., Bui. 98. 

101 



102 THE BOOK OF ICE-CREAM 

''Sensible heat. — Sensible heat is the heat that may 
be felt by the hand or measured by a thermometer. 

''Latent heat. — Latent or 'hidden' heat is the heat 
which is expended in molecular work of separating the 
molecules of the substance and can not be measured by 
a thermometer. Every substance has a latent heat of 
fusion, required to convert it from a solid to a liquid, and 
another, latent heat of vaporization, required to convert 
it from a liquid to a gas or vapor. Thus, if heat is applied 
to a pound of ice at 32° F. it will begin to melt, and no 
matter how much heat is applied, the ice will not get any 
hotter. After every particle of ice has melted, we will 
have 1 pound of water at 32° F., the same temperature 
as the ice before heat was applied. Experiments have 
shown that it requires 144 British thermal units to melt 
1 pound of ice at 32° F. into water at 32° F.; hence the 
latent heat of fusion of ice is said to be 144. 

"If heat is applied to 1 pound of water at 212° F., the 
water will remain at 212° F. under atmospheric pressure 
until all of it has been evaporated into steam at 212° F. 
This has been found to require 970.4 British thermal 
units; hence the latent heat of vaporization of steam at 
atmospheric pressure is said to be 970.4 B. T. U. 

"Specific heat. — The specific heat of a substance may 
be defined as the ability of that substance to absorb heat 
compared to that of water. Water being one of the 
hardest of all substances to heat, its specific heat is taken 
at unity. A better understanding of latent and specific 
heat may be had by studying the diagram in figure 42 
which shows graphically the relation of heat to temper- 
ature. 

"Ton refrigeration. — Refrigeration, or ice-melting ca- 
pacity, is a term applied to represent the cold produced, 



REFRIGERATION 103 

and is measured by the latent heat of fusion of ice, which 
is 144 B. T. U. per pound. In other words, it is the heat 
required to melt 1 pound of ice at 32° F. into water at the 
same temperature. The capacity of a machine in tons of 
^ice melting' or 'refrigeration' does not mean that the 
machine would make that amount of ice, but that the 
cold produced is equivalent to the melting of the weight 
of ice at 32° into water at the same temperature. There- 
fore 1-ton refrigeration is equal to 144 x 2,000, or 288,000 
B. T. U. A 1-ton refrigerating machine is a machine that 
has a capacity sufficient to extract from an insulated 
bath of brine 200 B. T. U. per minute, 12,000 B. T. U. 
per hour, or 288,000 B. T. U. per 24 hours. 

*' Absolute pressure. — Absolute pressure is pressure 
reckoned from a vacuum. Pressure gauges in general use 
are arranged to indicate pressure in pounds per square 
inch above atmospheric. To convert gauge pressure to 
absolute pressure, 14.7 pounds, the weight per square 
inch of air pressure at sea level, must be added." 

NATURAL ICE 

Only in the cold or northern latitudes can a supply of 
natural ice be obtained. In the warm regions a refriger- 
ating machine or ice made by an artificial refrigerating 
system must be used. The harvesting of ice is a very 
simple process, yet it involves a large number of details. 
Success in obtaining a crop of ice requires careful atten- 
tion to each detail. 

90. The ice field. — It is important that the water from 
which the ice is to be made be free from contamination. 
If weeds grow in the pond in the summer, they should be 
removed in the fall. If green spawn or algae grow pro- 
fusely, they can be eliminated by the use of copper sul- 



104 THE BOOK OF ICE-CREAM 

fate.* The crystals may be placed in a cloth sack, 
which is hung to a pole and trailed through the water 
until the salts are dissolved. One or two treatments of 
the sulfate in the season, at the rate of 1 pound to 
100,000 gallons (13,000 cubic feet) of water will be suffi- 
cient to keep down such growth and make the water 
clear and pure. The area of the ice field or pond should 
be large enough to fill the ice-house at a single cutting, 
some allowance being made for waste. The water should 
be deep enough so that there will be at least from eighteen 
inches to two feet under the ice at the time of harvesting. 
Snow often interferes with the ice formation. If the ice 
is thin, and the fall of snow heavy, the latter may sink 
the ice. If the snow remains on the ice, it acts as an 
insulator and so prevents the freezing. The snow may 
be handled in either of two ways; it may be scraped off 
the ice by hand or with a horse scraper, or the snow may 
be soaked with water. In the latter practice, there is 
danger of a crust forming and so preventing the formation 
of ice and hindering future scraping. 

91. The ice-house. — The main essentials of a good 
ice-house are insulation, ventilation, and drainage. The 
house should be so located that there will be good drain- 
age. If proper drainage is not provided, the water acts 
as a conductor of heat and so causes the ice to melt faster. 
It is desirable, but not necessary, that the ice-house have 
a north exposure and shaded with trees to keep off the 
heat of the sun. It should be located as near the place 
where the ice will be used as possible. There is a wide 
range of variation in type of construction and cost of 
materials in the erection of a satisfactory ice-house. The 

* Corbett, L. C, " Ice houses," U. S. Dept. Agr., Farmers Bui. 
475, 1915. 



REFRIGERATION 105 

walls may be insulated so that the ice is simply piled in 
the house. This is the most expensive type of construc- 
tion. In contrast to the insulated house, a bin may be 
built and the cakes of ice piled close together in it so that 
there will be a space about one foot to eighteen inches 
around the sides between the ice and the bin. This space 
should be filled with sawdust or hay and an equal amount 
placed over the top, which acts as an insulator. This is 
the cheapest form of construction and is somewhat waste- 
ful since the top of the pile is exposed to the direct rays 
of the sun and the rains. The usual type of ice-house is 
a form of construction between the two extremes men- 
tioned above. It consists of a cheap board frame to hold 
the insulation on the sides and a roof. The gables should 
be partly open to give a circulation of air. 

A cubic foot of ice weighs about 58 pounds and re- 
quires about 35 cubic feet for a ton. Allowance for 
the spaces between the cakes of ice should be made 
when figuring the capacity of the house. The usual 
practice is to figure from 43-46 cubic feet for each ton 
of ice. 

92. Harvesting and storing. — Ice is not usually har- 
vested until at least 8-12 inches thick. This will depend 
on the location and the season. The size of the cakes 
vary, but the usual sizes are 22 x 32 inches; 20-22 x 28; 
22 X 42-44. The cakes of ice may be sawed with a hand- 
saw. (Fig. 37.) 

On a large field, the ice may be cut with an ice-plow 
drawn by horses. (Fig. 38.) On this plow is a marker to 
show where the next cut should come. Thus if the first 
cut is straight, a straight mark will be made to be followed 
for each succeeding cut. The ice-plow does not cut en- 
tirely through the ice, but it should be adjusted to cut 



106 



THE BOOK OF ICE-CREAM 



nearly through. This will make the breaking off of the 
cakes easy. If the field is large enough, it is usually 
plowed each way. This cuts the ice into cakes. There- 
fore, after plowing all that is necessary is to separate the 
cakes. This is accomplished by breaking or splitting 




with a spHtting-fork. (Fig. 39.) On a small field, the ice 
is sometimes plowed only one way. In this case the 
cakes are sawed off with the hand-saw. 

Either a perpendicular or inclined elevation with their 
conveyors should be used to put the ice into the house. 
Only regular shaped cakes should be stored, all broken 




Fig. 38. — Ice-plow with marker. 

ones being rejected because they do not pack closely, 
hence allow too much waste and air space. The cakes 
should be packed closely together and yet allow air cir- 
culation. In order to secure this, it is best to run the rows 
of cakes one way in one tier, the other way in the next 
tier and so on. Each tier should be planed smooth before 
the next is placed on it. This may be done by a large 
planer on the ice incline or by hand in the house. The 



REFRIGERATION 107 

insulation should be put around the sides as the house is 
filled. When all the ice is in the house, the insulation, 
either hay or sawdust, should be immediately placed 
over the top. The ice should be watched and if the hay 
or sawdust has settled 
so that the ice is ex- ^ p— ' 1 — ' Q 

posed to the air, more ^^^ 39.-Splitting fork, 

should be added. It 

is best to fill the house when it is freezing temperature. If 
it is thawing the cakes of ice will have water on them, later 
this will freeze and it will be almost impossible to remove 
the cakes without breaking them. When taking the ice 
out, each tier should first be removed before the one be- 
low is disturbed. After each removal of ice the covering 
over the top should be replaced. 

93. Amotint of ice needed. — It is difficult to know 
exactly how much ice to store to meet the needs of the 
summer. Some ice goes farther than others; some years 
there is more waste than others. The following figures 
compiled by the ''Ice Cream Trade Journal" will give a 
fair idea of the amount required to a gallon of ice-cream: 
Amount of ice used for 100 gallons, 1,928 pounds. This 
was divided as follows: freezing, 614 pounds; hardening 
and storing, 914 pounds; shipping, delivering, and icing 
cabinets, 400 pounds. 

94. Use of ice and salt mixture. — Under normal con- 
ditions ice melts slowly. In order to obtain a quick 
change of temperature and one below that of the ice, a 
salt and ice mixture is used. Bo wen * gives the following 
discussion of cooHng by salt and ice mixtures: "When 
two solid bodies, as salt and ice, mix to form a liquid a 

* Bowen, John T., " The application of refrigeration to the hand- 
ling of milk," U. S. Dept. Agr. B. A. I., Bui. 98. 



108 



THE BOOK OF ICE-CREAM 



certain amount of heat becomes latent, called the latent 
heat of solution. Since this latent heat is taken from the 
mixture itself the temperature falls correspondingly. 



30 


\ 














25 


\ 


\ 












20 


1 


\ 












/5 


i 




\ 










/O 


1 




\ 


\ 








5 


1 






\ 















\ 


1 






'5 


^ 
«: 

T 








\ 






'/O 


X 


% 


or sa 


\Lr 


\ 







o 

Fig. 40.- 



/O 



/5 PO 25 30 



-Approximate temperatures obtained with different 
proportions of ice and salt. 



The temperature obtained by a salt and ice mixture de- 
pends principally on the relative proportions of the mix- 
ture, and to a less extent on the rate at which the heat is 



REFRIGERATION 



109 



supplied from the outside, the size of the ice lumps and 
salt particles, and the amount and density of the resulting 
brine. Hence it is impracticable to give other than approx- 
imate temperatures with fixed ratios of salt and ice. The 
following curve (Fig. 40) shows the approximate tempera- 
ture obtained with different proportions of salt and ice. 
''One pound of ice, in melting, absorbs 144 B. T. U. 
This is known as the latent heat of fusion of ice. Salt in 
dissolving also absorbs heat, called the latent heat of 



/-f5 



/40 
kj /20 



//O 



1 
\/05 





























"^ 




*-. 






















t 




^ 




V^ 


















t 

^ 








\ 




v^ 














^ 

J^ 












\ 






























\ 


\ 








^ 




















\ 


N 


























^ 


\ 


«j 
































% 


or s. 


ALT J 


A/ A// 


XTO 


RE 











2^ 6 <3 /O /2 M /6 /8 20 22 24 
Fig. 41. — Refrigeration available with different percentages of salt. 

solution, which varies in amount, depending on the 
density and temperature of the resulting brine. 

"The heat of solution of salt in water at 32° F. varies 
from 58 to 16 B. T. U., depending on the final strength of 
the brine obtained. 

"The following curve (Fig. 41) shows the amount of 
refrigeration available per pound of ice and salt mixture. 
The figures were calculated from the melting of ice at 



110 THE BOOK OF ICE-CREAM 

32° F. into a liquid at the same temperature. If, however, 
the salt is added to the ice at a temperature varying from 
32° F. or, if the resulting brine is allowed to escape at a 
temperature other than 32° F., the amount of available 
refrigeration must be corrected accordingly. These 
corrections are determined by multiplying weights, in 
pounds of salt and brine, by their respective specific heats 
and by their difference in temperature from 32° F. The 
specific heat of dry salt may be taken as 0.214, as the 
specific heat of salt brine varies with its density. 

"Usually salt when added to ice is of a higher temper- 
ature than that of the ice; consequently the correction for 
its heat above 32° F. must be subtracted' from the available 
refrigeration shown by the curve, Fig. 41; and if the brine 
is allowed to escape at a temperature below 32° F. the re- 
frigeration lost in the discharge brine must be subtracted, 
while, on the other hand, if the discharge brine is at a tem- 
perature higher than 32° F. the correction must be added. 

"If given amounts of ice and salt, at a temperature of 
32° F. are mixed together and the mixture supplied with 
sufficient heat to melt the ice and dissolve the salt and 
raise the temperature of the resulting brine to the original 
temperature of 32° F., then the total amount of heat 
absorbed by the reaction will be the sum of the latent 
heat of the ice and the heat of solution of the salt to form 
the resulting brine of the density which will result from 
the particular proportion of salt and ice chosen. As an 
example, under the foregoing conditions, if 100 pounds of 
dry salt are added to 900 pounds of ice the total available 
refrigeration is 1,000 x 133= 133,000 B. T. U. The avail- 
able refrigeration per pound of mixture, 133 B. T. U., is 
taken from the curve in Fig. 41. If the salt added is at 
a higher temperature than 32° F., say 60° F., then the 



REFRIGERATION 111 

available refrigeration will be 133,000 -[100 x 0.214 (60- 
32) ] = 132,401 B. T. U., or 132.4 B. T. U. per pound of 
mixture. If the resulting brine is allowed to escape at 
25° F., the available refrigeration is 133,000- [1,000 x 
0.892 (32-25)] = 126,756 B. T. U., or 126.7 B. T. U. 
per pound of mixture. Or, in other words, there is lost in 
the first case 100 x 0.214 (60-32) =599 B. T. U., and in 
the second case, 1,000 x 0.892 (32-25) = 6,244 B. T. 
U., or a total loss, if the salt is added at 60° F. and the 
brine allowed to escape at 25° F., of 599+6,244 = 6,843 
B. T. U. Under these conditions the available refrigera- 
tion is 133,000-6,843 = 126,157 B. T. U., or 126 B. T. U. 
per pound of mixture." 

MECHANICAL REFRIGERATION 

A large number of small ice-cream plants do not use 
mechanical refrigeration, but natural ice. It is not con- 
sidered economical either in labor or cost to attempt to' 
employ ice if seventy-five or more gallons of ice-cream are 
made a day. The size of the mechanical refrigerating ma- 
chine varies, but the underlying principles are the same. 

95. Principles of mechanical refrigeration. — Bowen 
gives the following concise but plain description of these 
principles: * 

''When a solid or a liquid changes its state or condition, 
as when a solid is converted into a liquid or a liquid into 
a gas or vapor, the change of state or condition is in each 
case accompanied by the absorption of heat. This ab- 
sorption of heat, as previously explained, is called ' Latent 
Heat'; that is, heat that cannot be measured by a ther- 
mometer; and in order to transfer a substance from one 

* Bowen, J. T,, " The application of refrigeration to the handling 
of milk," U. S. Dept. Agr. B. A. I., Bui. 98. 



112 THE BOOK OF ICE-CREAM 

state to another it is only necessary to supply or extract 
heat. For instance, if we take 1 pound of ice at zero 
temperature, Fahrenheit scale, and apply heat, the tem- 
perature will rise until it reaches 32°. If we continue the 
appHcation of heat, the ice will begin to melt, and after 
we have supphed sufficient heat the 1 pound of ice will 
have changed to water at 32° F., the same temperature 
at which the ice commenced to melt. If the application 
of heat is continued the water will grow warmer, but at 
a slower rate. It now takes about double the amount of 
heat to raise the 1 pound 1 degree as water that it did to 
raise the 1 pound 1 degree as ice. In other words, the 
specific heat of water is approximately double that of ice. 

''When sufficient heat has been added to raise the 1 
pound of water to a temperature of 212° F., another 
critical point is reached at which further application of 
heat to the water, under atmospheric pressure, will not 
increase its temperature, but changes it into steam at a 
temperature of 212°. The relation of heat to temperature 
is shown in Fig. 42. 

''It will be noted from Fig. 42 that to raise the temper- 
ature of the 1 pound of ice from zero to the melting point 
(32° F.) 16 B. T. U. were expended; in melting the ice, 
144 B. T. U.; in raising the water to the boiling point, 
180 B. T. U.; and to evaporate the water, 970.4 B. T. U. 
If the operation is reversed, the heat being extracted 
instead of being added, the curve will follow backward 
on itself to the starting point. 

"The latent heat of fusion and the latent heat of vapor- 
ization are represented on the diagram by the two lines 
parallel to the horizontal base line, the length of the lines 
representing to scale the amount of heat expended in 
molecular work in separating the molecules of the sub- 



REFRIGERATION 



113 



stances. Starting from the left, the rising Hnes represent 
the heat required to raise the temperature of the ice, 
water, steam at constant volume, and steam at constant 
pressure, respectively." 

96. Materials used in mechanical refrigerating sys- 
tems. — "The same law applies to liquified anhydrous 
ammonia, carbon dioxid and sulphur dioxid, which are 



^'^n 










































... 




~ 


~ 


Jl\ 


^PO 






























SreAM CO/VS7>!\A/r l/Oli/Af£— 




/ 


"^00 
































5T€A/^ COA/STANT F'/^SSSORE- 




/ 


F»n 


























































?6n 


























































P'iO 


























































??n 


is 


























































^ 












1 












































?oo 








































IfitO 


i- 












/ 












































f6n 












/ 












































/4n 


























































/?o 








,^ 
















































too 








f 
















































so 






















































60 








t 


















































^n 




/Cl 




/ 






















































/ 


















































pn 


/ 









L 


















QU. 


^A/T/T) 


•< OF J- 


^SA 


T/ 


V J 


?. Z 


U 





















PM 300 400 500 600 700 SOO 900 /OOO //OO /SOO /300 

Fig. 42. — Diagram showing relation of heat to temperature. 

the substances most commonly used in commercial re- 
frigerating machines. These liquids are extremely volatile, 
their change of state takes place very rapidly, and their 
latent heat is absorbed at a corresponding rate. Their 
boiling point is sufficiently low, under atmospheric or 
other conveniently produced pressure, to give the tem- 
perature desired. Although the same principles underlie 
the use of all such fluids, their physical properties vary, 
and consequently demand different treatment in order 
to produce the best results. 



114 THE BOOK OF ICE-CREAM 

"The theoretical requirements of a good refrigerant 
are: A low boiling point at ordinary pressure, a large 
latent heat of vaporization, and a small specific volume. 
A low boiling point is desirable, because it makes opera- 
tion possible with comparatively low pressure in all parts 
of the system; therefore, the machines and accessories 
may be of lighter construction, with smaller loss of gas 
by leakage. As the latent heat of vaporization is, to a cer- 
tain extent, a direct measure of the cooling effect, it is 
obvious that the greater the heat of vaporization the better 
the refrigerant. The specific volume of the refrigerating 
agent determines the volume of the cylinders of the com- 
pressor, consequently the size and weight of the machine. 

''In comparing the three refrigerating agents which 
are considered apphcable to the dairying industry, viz., 
ammonia, carbon dioxid, and sulphur dioxid, it will be 
noted by referring to tables giving the main character- 
istics of the agents that, assuming the limits of operation 
are between 5° F. and 85° F., the absolute pressures are: 
Ammonia from 27 to 175 pounds, carbon dioxid from 
290 to 1,000 pounds, and sulphur dioxid from 9 to 65 
pounds. Taking the boiling points of the liquids at the 
temperature at which the liquid boils under atmospheric 
pressure, it will be noted that there is a wide difference 
in their boiling points as well as their latent heats of 
vaporization. Ammonia boils at 28.5° F. below zero and 
has a latent heat of vaporization of 572.8 B. T. U. Car- 
bon dioxid boils at 110° F. below zero and has a latent 
heat of vaporization of 140 B. T. U. at a pressure of 182 
pounds per square inch absolute. The latent heat at 
atmospheric pressure is not definitely known. Sulphur 
dioxid boils at a temperature of 14° F. and has a latent 
heat of vaporization of 162.2 B. T. U. 



REFRIGERATION 115 

'Tor practical purposes the value of a refrigerant 
depends upon its boiling point, its latent heat of va- 
porization, and upon the pressure at which it can be 

used. 

''To maintain a zero temperature with ammonia as 
the refrigerant an absolute pressure of 30 pounds per 
square inch is required in the evaporating coils; with 
carbon dioxid, 310 pounds absolute; and for sulphur 
dioxid, 10 pounds. 

"Ammonia has a much greater latent heat of vapor- 
ization and the working pressures are not excessive, but 
it has the disadvantage that it corrodes brass or any 
other copper alloy; consequently only iron or steel can 
be used in the construction of those parts of the machine 
with which the agent comes in contact. The pressures 
of carbon dioxid are so' high as to cause trouble in keeping 
the stuffing box and joints tight. A relief valve is often 
placed in the high-pressure side of the system in order to 
protect it from excessive high pressures. It is noncor- 
rosive, nonexplosive, and is not dangerous to life when 
diluted with air. The high pressures necessary, combined 
with the small specific volume of the gas, make it suitable 
for use with a very compact machine. As the lower 
pressure of sulphur dioxid is below the atmospheric, any 
leakage of air will be into the system and will cause cor- 
rosion of the metal by forming sulphurous acid. The 
low pressures required in using sulphur dioxid as a re- 
frigerant in connection with its large specific volume 
makes a large and cumbersome machine necessary. The 
ratios of the volumes of the cylinders necessary for a 
given capacity of machine, taking that of carbon dioxid 
as one, are approximately as follows: Carbon dioxid 1, 
ammonia 4.4, sulphur dioxid 13." 



116 



THE BOOK OF ICE-CREAM 



97. Operation of refrigerating machines. — The re- 
frigerating material commonly used in ice-cream plants 
is ammonia. There are two types of ammonia machines, 
the compression and the absorption systems. 

98. The compression system. — The following, Fig. 43, 
shows the simplest compression system of refrigeration. 
The liquid ammonia in the small container is allowed to 

evaporate but it really 
boils. In order to boil 
or to change from a 
liquid to a gas, it 
must absorb heat. 
This heat is taken 
from the surrounding 
material, in this case 
brine. This cools the 
brine in the container 
in which the vessel 
of ammonia is placed. 
In this case, there is 
no control of the rate 
of evaporation of the 
ammonia. 

An arrangement by which the evaporation or escape 
of gas can be controlled is shown in Fig. 44. The flow of 
liquid is regulated by an expansion valve and the liquid 
is carried into a brine tank or refrigerating room and from 
the coil of pipe in there gas is allowed to escape in the 
atmosphere. The change from a liquid to a gas in this 
coil of pipe cools the surrounding substance, either brine 
or air. Tiiis is the usual arrangement of the compression 
system; the remainder of the system is to return the evap- 
orated liquid or gas back to a liquid in the ammonia tank. 




Fig. 43. — Simplest compression system 
of refrigeration. 



REFRIGERATION 



117 



99. Parts of a compression system. — The functions 
and principal parts of a compression system of refrigera- 
tion are as follows : 

Compressor, — This is a specially designed valve pump. 
It takes the gas from the evaporating coils, compresses 




Fig, 44. — Compression system of refrigeration in which the flow of 
liquid is regulated by the expansion valve. The liquid changes 
to a gas in the coil of pipe, thereby cooling the brine. The gas 
finally passes off into the atmosphere. 

it and forces it into the condensing coils. This reduces 
its volume and produces heat. 

Oil-traps. — In the compressor, there is danger of some 
oil becoming mixed with the ammonia. The purpose of 
the trap is to separate the oil from the ammonia. It is 
usually placed next the compressor. 

Condensing coils. — This consists of a double coil of 
pipe, one within the other. Cold water is circulated in 
the inner pipe and the ammonia in the space between 
the inner and outer pipe. In the condensor the heat is 



118 



THE BOOK OF ICE-CREAM 



taken up by the water and the ammonia again becomes 
a liquid. 

Ammonia receiver or storage tank. — From the condens- 
ing coils, the liquid ammonia passes into a receiving or 
storage tank until wanted for use again. 

Expansion valve. — It is by means of this valve that the 
evaporation of the ammonia is regulated or, in other 
words, the rate of flow of the ammonia from the receiving 
tank is regulated by this valve. 



EVAPORATING COIL- 



0/L SEPARATOR 




WATER /NLET fl . DOUBIE P/RE 

AMMONIA CONDENSER 



AMMONIA RECEIVER 




Fig. 45. — Complete system of direct expansion refrigerating machine. 



Evaporating coils. — These coils are usually located in 
the material to be cooled, ordinarily the air of the re- 
frigerator or a brine tank. In these coils, because of the 
reduced pressure, the ammonia liquid evaporates or boils 
and in doing so takes up heat. This, as has been explained 
before, causes the cooling. From the evaporating coils 
the ammonia gas goes back to the condensor. This 
makes a complete circuit for the ammonia. 

100. Operation of direct expansion compression sys- 
tem. — The following diagram. Fig. 45, shows the complete 
system of direct expansion refrigerating. When the 
evaporation coils are placed in the refrigerator and the 



REFRIGERATION 119 

heat is taken directly from the air, it is known as the 
direct expansion system. 

The Kquid ammonia passes from the ammonia re- 
ceiver (R) through the expansion valve (X) into the 
evaporating coils (E). Here the ammonia changes from 
a liquid to a gas and in so doing takes up heat from the 
refrigerator. The ammonia gas passes to the compressor 
(C). From the expansion valve to the compressor is 
what is usually known as the low pressure side because 
here the pressure is reduced in order that the ammonia 
can boil or evaporate. For this reason the expansion 
valve is sometimes called the reducing valve. The gas 
is compressed in the compressor (C), then passes through 
the oil-trap (S) where the oil is taken out and then through 
the condensing coils (W) where the heat is absorbed and 
the gas changed to a liquid and back to the ammonia 
receiver (R). From the compressor to the expansion 
valve is what is known as the high side because of the 
pressure caused by the compression. 

101. Location of evaporating coils. — As explained 
above, the location of the evaporating or expansion coils 
in the refrigerator so that the heat is taken directly from 
the air is known as the direct expansion method of re- 
frigeration. In order to keep a refrigerator cold with this 
method, it is necessary to run the compressor almost 
continuously. In some cases the evaporating or expan- 
sion coils are placed in brine tanks. The heat is then 
taken from the brine which in turn cools the air. By the 
use of th,e brine tanks, the compressor may be stopped 
and the cold brine will tend to maintain a more uniform 
temperature in the refrigerator while the compressor is 
not running. 

A combination of the direct expansion and brine storage 



120 



THE BOOK OF ICE-CREAM 



tanks is shown in Fig. 46. This is a common arrangement 
in refrigerators where a low temperature is desired and it is 
not economical to run the compressor continuously. The 
brine storage tanks are sometimes called congealing tanks. 
In some cases it is desirable to have refrigeration in 
some place where it is not possible to use either the direct 
expansion or the brine storage system; for example, to 
freeze ice-cream. In this case the expansion coils are 
located in a brine tank and the cold brine pumped to the 
place where refrigeration is desired. Such an arrange- 



£^/APORATir\lG CO/L- 




FiG, 46. — Combination of direct-expansion and brine storage tanks. 
This is the same system as shown in Fig. 45 with the brine 
tank T added in the refrigerator. 

ment is shown in Fig. 47. The brine flows from the tank 
(T) in the refrigerator to the pump (P) . It is then pumped 
through the ice-cream freezer (I) and back to the brine 
tank. The latter may be separate from the refrigerator 
and contain cans of water for the making of artificial ice. 
Most plants make artificial ice for packing the ice-cream 
for delivery. . 

102. Notes on operating compression system. — In 
order to operate a refrigerating machine economically, 
certain factors must be given constant attention. When 
ammonia is passing through the expansion valve, it 



REFRIGERATION 



121 



should be covered partially with frost or the part where 
the pressure is reduced will be frosted as will the pipe 
leading from it into the refrigerator. This cannot be 
prevented. The proper adjustment of the expansion 
valve is very important. If too wide open, the flow of 
liquid will be too rapid, it will not all vaporize in the 
evaporating coils and so will take heat from the air after 
leaving the refrigerator, causing the pipe from the re- 
frigerator to the compressor to become covered with 




Fig. 47. — Arrangement where it is desired to use cold brine in some 
machine such as an ice-cream freezer. This is the same refrig- 
erating system as shown in Figs. 45 and 46. 



frost. This is a waste and may cause a high pressure on 
the low side. 

Usually the low pressure side carries 10-20 pounds 
pressure and the high side 125-150 pounds. 

If the ammonia passes the expansion valve too fast, 
as mentioned above, it may cause the compressor to 
labor too hard and so cause pounding. If not enough 
ammonia is passing the expansion valve, the rate of re- 
frigeration is reduced. 

The cost of operating a refrigerating machine varies. 
The principal items are: 1, Power; 2, water; 3, incidentals 
(refrigerant oil, and the like); 4, repairs. No figures can 



122 THE BOOK OF ICE-CREAM 

be given for the cost of a ton of refrigeration because of 
the variation in the price of each of the items mentioned. 
Some very compact refrigerating systems are on the 
market especially adapted for making ice-cream in places 
where space is limited. The principle of operation of 
these machines is the same as all other expansion systems. 

ABSORPTION SYSTEM 

The absorption system is not as common -as the com- 
pression. When used, it seems to be very satisfactory. 

103. Operation of absorption refrigerating system. — 
The following principles of operation, and Fig. 48 of an 
absorption refrigerating machine, are contributed by 
Henry Vogt Machine Company. 

"The first step is pumping a strong charge of what is 
technically known as aqua ammonia, or, in plain terms, 
a solution of water and anhydrous ammonia, from the 
absorber into the bottom pipe of th6 rectifier. It is then 
forced upward through the inner pipes or tubes and out 
from the top through a pipe connected to the top of the 
exchanger where the strong liquid passes down through 
the inner pipes or tubes and out at the bottom through 
a pipe connecting with the ammonia generator. 

''Within the generator the ammonia gas is driven off 
from the strong solution by the heat in the steam coils, 
leaving a weak solution of aqua ammonia in the lower 
part of the generator. 

"The generated gas, under pressure passing out at the 
top of the generator, enters the rectifier through the top 
connection and is forced downward through the outer 
pipes. In, transit through the rectifier, the strong aqua 
absorbing some of the heat in the gas, condenses whatever 
moisture is in it. The gas passes out of the bottom of the 



REFRIGERATION 



123 




U3 1 J 1X33)1 01 SV9 



124 



THE BOOK OF ICE-CREAM 




REFRIGERATION 125 



1. H. P. gas; 2. Purge; 3. Water outlet; 4. Purge; 5. H. P. trap; 
6. H. P. gas; 7. Purge; 8. Water; 9. to sewer; 10. Purge; 11. 
Purge drum; 12. Equalizing main; 13. Purge; 14. Steam coils; 
15. Trays; 16. Pump-out; 17. Drain; 18. Gauge board; 19. 
Oil trap; 20. Exhaust steam; 21. Trap; 22. Weak aqua main; 
23. Strong aqua main; 24. Boiler steam; 25. Aqua ammonia 
pump; 26. Exhaust; 27. Drain; 28. Pump-out; 29. Pump-in; 
30. Pump-out; 31. Gauge lines, 32. Equalizing main; 33. 
S. A. Draw-off; 34. Charging connection; 35. Charging connec- 
tion; 36. Drain; 37. Check; 38. L. P. Gas; 39. Ammonia liquid ; 
40. Weak aqua; 41. Regulating valve; 42. Water outlet; 43. 
W. A. Draw-off; 44. Check; 45. Liquid mains; 46. Accumulator 
W. A. Draw-off; 44. Check; 45. Liquid mains; 46. Accumula- 
tor; 47. outlet; 48. Drip; 49. Fresh water main; 50. check; 
51. Expansion valve. 



126 



THE BOOK OF ICE-CREAM 




<D 




^ 




-M 




-7:3 




rt 




03 




m 




fl 




O 








■+-> 




o 




o 




fl 




el 




o 




O 




<u 




4:3 




-t-J 




bf) 




fl 








n 


^ 


02 


U 
« 




00 


0) 


0) 


!=1 


03 


^ 


bU 




n1 


'^ 


a 


^ 





TO 


-fj 


;=! 


a 


a' 









'""' 


tc 


a> 


-9-^ 


o3 


-t-j 





^ 


h 


« 




^ 
^ 


(/J 



a 




a 


03 


u 




>J 







0) 


+j 


fi 


PI 




OJ 




a 




QJ 




bO 




C 




crt 




Jh 




tn 




03 








03 




}-i 




(V 




SH 




O) 





1 




1 
d 




»o 




d 








PIH 





REFRIGERATION 127 



1. Water main; 2. Purge; 3. Purge; 4. H. P. Trap; 5. H. P. Gas; 
6. H. P. Gas; 7. Drip; 8. Check; 9, Strong aqua; 10. Drip; 
11. Pump-out; 12. Weak aqua; 13. Gauge; 14. Traj^s; 15. 
Steam coils; 16. Gauge glass; 17. Boiler steam; 18. Exhaust 
steam; 19. Grease trap; 20. Drain; 21, Gauge board; 22. 
Liquid main; 23. Strong aqua main; 24. Weak aqua main; 
25. Gauge; 26. Trap; 27. Aqua ammonia pump; 28. Exhaust; 
29. Drain; 30. From boiler; 31. Air chamber; 32. Pump-in; 33. 
Equalizing main; 34. Charging connection; 35. Pump-out and 
blow-in; 36. Drain; 37. Charging connection; 38. Blow-in line; 
39. Gauge line; 40. Liquid main; 41. Accumulator; 42. Ex- 
pansion valve; 43. Purge; 44. Purge drum; 45. Water main; 
46. EquaHzing main; 47. Gas main; 48. Check; 49. W. A. 
main; 50. W. A. Draw-off; 51. Strong Aqua tank; 52. Gauge 
glass; 53. S. A. Draw-off; 54. Check. 



128 THE BOOK OF ICE-CREAM 

rectifier into a separator where baffle plates separate the 
moisture from the gas. 

"The moisture is trapped back to the generator while 
the dry gas continues to the condenser, where it enters 
at the top of the shell or coils. Being brought into con- 
tact with the water cooled surface of the condenser, the 
sensible as well as the latent heat of the ammonia is ex- 
tracted, and the gas quickly liquifies. This liquid am- 
monia is conducted to the brine cooler or refrigerating 
coils where it evaporates by absorbing the heat contained 
in the brine or air surrounding the coils, thus performing 
the work of refrigeration. The vapor or gas thus formed 
is piped to the bottom of the absorber. 

''The weak aqua ammonia, in the meantime, passes 
from the bottom of the generator to the bottom of the 
exchanger and flows upward through the outer pipes for 
the purpose of exchanging the heat with the strong aqua 
ammonia flowing downward through the inner pipes. 

''From the top of the exchanger the weak aqua is 
conducted to the bottom of the weak aqua cooler, flowing 
up through the outer pipes to be further reduced in tem- 
perature by cooling water passing down through the 
inner pipes. Finally it flows in the top of the absorber 
where the ammonia vapor from the refrigerating coils, 
owing to its great affinity for water, is rapidly absorbed 
by the weak aqua, forming again the strong solution of 
aqua ammonia. The double cycle of circulation is thus 
completed. The same operation is repeated indefinitely." 

104. Arrangement of double pipe and atmospheric 
absorption machines. — There are several types of the 
absorptiqn machines. The general arrangement and the 
direction of the flow of gases and liquids are shown in 
Figs. 49 and 50. 



CHAPTER IX 
PREPARING THE MIX 

Mix is a term applied to the unfrozen ice-cream. It is 
sometimes called ^' batch" or '^batter." The amount of 
mix prepared at one time may be enough for one or sev- 
eral freezers or for a whole day's freezing. 

105i Importance of preparing the mix. — The pre- 
paring of the mix is one of the most important phases of 
the ice-cream business, because of the control of flavor, 
the effect on the body and texture, and financial consider- 
ations. 

If the flavors were always uniform, it would be a simple 
matter to prepare the mix. This not being the case, it 
requires considerable practice and skill to know exactly 
how to blend them. The mixer of the different materials 
should know which must be rejected and which used and 
in what flavors of ice-cream. The sour or acid flavor can 
be determined easily in the milk products by means of the 
acid test. For its use, see Chapter XIV. Besides this, 
many other undesirable flavors are present in the ma- 
terials. For example, it would be unwise to try to mix 
acid fruits with cream already high in acid, since this 
probably would cause a pronounced sour taste and might 
curdle the cream. Some makers believe that the flavor 
added to the ice-cream will cover up any bad flavors in 
the milk products, but this is not the case. If there is 
any undesirable flavor in the materials it can be detected 
in the ice-cream. Of course the person preparing the mix 

129 



130 THE BOOK OF ICE-CREAM 

has the receipt or formula but this is only a general guide; 
the final test is the taste. Each mix should be tasted 
before it is frozen to make sure that the flavor is correct. 
If not palatable in the mix, it will not be in the ice-cream. 
In some cases, it is necessary to have the flavor more 
pronounced in the mix than is desired in the finished 
product because the flavor may freeze out or become less 
pronounced. 

From the financial viewpoint, mixing is one of the most 
important parts of the whole enterprise. Here the ques- 
tion of whether the business is to be a success or failure 
is largely determined by the cost of the materials. After 
the materials have been determined, it is necessary to 
see that the exact amount is used in each mix. This 
means that each mix must be standardized, both for fat 
and total solids. For method of standardization, see 
Chapter XIV. An example may illustrate what a small 
loss will amount to in dollars and cost a gallon. Suppose 
1000 pounds of cream testing 20 per cent fat were desired 
and instead of this it tested 20.5 per cent fat. This would 
use 5 pounds more fat which at $1.00 a pound would 
equal $5.00; the wages for a good man. This 1000 pounds 
of cream would make approximately 250 gallons of ice- 
cream. The $5.00 additional cost for 20.5 per cent cream 
would make the ice-cream cost 2 cents a gallon more. 
This shows that a small divergence in cost a gallon may 
make a big total difference especially noticeable if near 
the dividing line between profit and loss. Another ex- 
ample indicates how carefully the mix may be standard- 
ized to reduce cost. An ice-cream plant found that the 
mix could contain .21 per cent of acidity without injury 
to the quahty of the product. Each material was tested 
for acidity (see Chapter XIV), and because there was an 



PREPARING THE MIX 131 

abundant supply of buttermilk for which there was no 
market, the mix was standardized to .21 per cent acidity 
by the use of buttermilk. This reduced the cost by using 
a material for which there was no market. The body and 
texture are largely determined by the materials employed, 
although the freezing and subsequent handling has a 
decided influence on the quality. 

Too much study cannot be given to the question of the 
materials to be used in the mix nor too much pains taken 
to see that each mix is properly standardized. 

106. Usual procedure in preparing the mix. — Much 
detail variation in preparing the mix is possible and yet 
obtain accuracy and good quality of ice-cream. The 
usual procedure is as follows: The milk products are 
first put into the container in which the mixing is to be 
done. In a large ice-cream plant some type of the me- 
chanical mixer, Figs. 20, 21, 22, 23, and 24, is used. A 
view of a mixing-room is shown in Fig. 51. The mixers 
are just above the level of the floor, making it easy to put 
materials into them. In this case, the mixers are above 
the freezers so that the mix flows by- gravity. Each 
material should be weighed or measured accurately. 
After the materials are mixed together, it is often desirable 
to test them to make sure that the desired standardiza- 
tion has been obtained. The sugar is weighed next into 
the mix. The amount will vary according to the flavor 
and materials used. For example, with sweetened con- 
densed milk, less sugar will be required. Time should be 
allowed before freezing for the sugar to dissolve. This 
can be hastened by stirring, which may be done by a 
mechanical or hand agitator, depending on the size of 
the mix. Whichever method is employed, care should 
be exercised not to stir the mix enough to cause the fat 



132 



THE BOOK OF ICE-CREAM 



to churn. This would cause lumps of fat or butter in the 
ice-cream. 

The stabilizer is added next. In some cases, such as 
the prepared ice-cream powders, it should be mixed with 




Fig. 51. — Mixing room in large ice-cream plant. 

the dry sugar and added with it. If gelatine or gum 
tragacanth is used, it should be applied slowly and the 
mix agitated to prevent lumps forming. For method of 
preparing gelatine, see Chapter IV. If color is desired, 
it should be put in just before the flavor. This will pre- 
vent streaks in the ice-cream. Lastly, the flavor should 
be added, care being taken to use the exact amount. In 



PREPARING THE MIX ' 133 

the case of fruit ice-cream, the fruit may not be put in 
until the mix is partly frozen. If acid fruits are stirred 
in the mix before partly freezing, the cream might curdle. 
If the fruit is added to the mix and then frozen in an 
upright freezer, there is danger of it settling to the bottom. 

If it is desired to emulsify or homogenize the whole 
mix, this should be done before the flavoring materials 
are added. The flavoring might be lost during the proc- 
ess and pieces of fruit would clog the machine. 

When ready to freeze, the mix should be tasted to 
make sure that everything has been added and that the 
mix has the proper flavor. Of course little can be told 
about the body and texture of the resulting product by 
tasting the mix. But the flavor is a good index of that 
of the ice-cream. 

107. Temperature of the mix. — As will be pointed 
out in connection with over-run, the temperature of the 
mix when it enters the freezer is very important. If too 
warm, the cream will churn before it will beat up or whip. 
Most of the mechanical mixers possess some means of 
controUing the temperature of the mix. But the operator 
should make sure that the mix is at the desired temper- 
ature. It should never enter the freezer above 60° F. and 
the nearer 40° F. the better. 



CHAPTER X 

FREEZING PROCESS 

The principles of freezing are the same whether a 
large or small freezer is employed. It is usually harder to 
control the process in a small receptacle. In a large plant 
the freezers are arranged in a row or battery, as shown 
in Fig. 52. One man operates six to eight, with a helper 
to carry the ice-cream to the hardening-room. 

108. Purpose of freezing. — Freezing is for the purpose 
of cooling the mix and getting it in such condition that 
it is edible while frozen. If frozen without agitation it 
would be icy and grainy. If the mix is placed in the 
freezer too warm, it is liable to churn. Freezing incorpo- 
rates air into the ice-cream and so gives pore space. The 
increase in volume due to freezing is known as "swell" 
or ''over-run." 

109. Rate of freezing. — If the freezing is not properly 
done, the result is a loss in both quality and quantity 
of ice-cream. The rate or time required to freeze is af- 
fected by different factors, depending on the type of 
machine used. 

In the brine freezer, the rate is dependent on the follow- 
ing factors: 1. Temperature of brine; 2. rate of flow of 
brine; 3. temperature of materials when put into freezer; 
4. materials in mix; 5. speed of the freezer. 

In the tub and can freezer the rate is dependent on the 
factors: 1. Proportion of salt and ice; 2. amount of brine; 
3. mixture of salt and ice and brine; 4. speed of freezer; 

134 



FREEZING PROCESS 



135 




136 THE BOOK OF ICE-CREAM • 

5. temperature of materials when put into freezer; 6. 
materials in mix. 

Ice-creani should not be frozen too fast or too slowly 
nor for too long or short a period. If the extremes occur, 
the quality and quantity are affected. 

Results of freezing too rapidly: 

1. Cannot obtain swell. 

2. Causes cream of poor quality. 

1. Soggy or heavy — due to lack of air space. 

2. Grainy in texture. 

3. Does not hold well in storage. 

Results of freezing too slowly: 

1. Cream is liable to churn, causing chunks of butter 

in the ice-cream. 

2. Greasy ice-cream. 

3. Cannot obtain swell. 

4. Ice-cream usually lumpy. 

. Results of not freezing enough: 
1. Ice-cream is watery. 
2; Ice crystals separate while hardening 

3. Do not obtain proper swell. 

4. Fat rises to surface of the ice-cream. 

Results of freezing too much or too long: 

1. Liable to churn cream. 

2. Lose swell. 

3. Ice-cream is liable to be greasy. 

4. Ice-cream is soggy and heavy. 

The rat^ of freezing can be regulated much easier in 
the brine than in the tub and can freezer. In the former 



FREEZING PROCESS 137 

the condition of the ice-cream can be seen without stop- 
ping the machine, and also the temperature taken. On 
the other hand, with the tub and can freezer, the machine 
must be stopped each time and the cover removed in 
order to see the condition of the ice-cream or to take the 
temperature of it. With the brine freezer the rate of 
flow of the brine can be regulated. The temperature of 
the brine alone is not important, but the rate of flow 
must be considered. In the tub and can freezer the pro- 
portion of -ice and salt can be regulated, but this is not 
very satisfactory. The ratio of salt to ice regulates the 
rate of freezing. (See page 108.) Usually one part salt 
to twelve to eighteen parts of ice is the correct proportion. 
The finer the ice and salt, the more rapid the freezing. 

The rate of freezing is also affected by the amount of 
sugar and solids in the ice-cream. The effect of sugar on 
the temperature is shown in Table V. 

Table V 

Effect of sugar on freezing 

Percentage of sugar Temperature of freezing 

in solution Degrees F. 

Skim-milk 31.03 

5 per cent solution of sugar 30 . 40 

10 per cent " " " 29.70 

14 per cent " " " 28.60 

25 per cent " " " 27.07 

The effect of a large percentage of sugar on the freezing 
is especially noticeable in the case of sherbets and ices. 
These freeze much slower than ice-cream. 

110. Proper method of freezing. — The question might 
be asked as to the proper way to freeze ice-cream. Be- 
cause of the many factors involved, the only direct answer 
is to state that the process should result in a mellow body, 



138 THE BOOK OF ICE-CREAM 

smooth texture and medium swell. The colder the mix 
when it enters the freezer, down to 40° F., the better the 
control. It should take from twelve to twenty minutes 
to freeze. The mix should be cooled quickly to 32° F., 
then the flow of brine partly shut off and the cream al- 
lowed to whip. When the cream is nearly whipped, 
the brine should be turned on gradually and the cream 
allowed to freeze. When the mix is partly frozen, the 
fruit should be added, soon enough so that there will be 
time for it to become uniformly distributed in the mix. 
It is the usual practice to crush the whole fruits before 
putting them in the freezer. This can easily be done by 
forcing them through a food chopper. The cream should 
come from the freezer at a temperature of 26° F.-28° F. 
The appearance of the ice-cream and its temperature is 
a good index when frozen enough. It should have its 
peculiar characteristic (dead) not shiny appearance. 
When the thermometer is placed in the freezer and drawn 
out, the ice-cream should adhere to it and the part re- 
maining on the thermometer should retain its identity 
for a few minutes. 

Experiments * show that between 29° F. and 26° F., 
the volume of the ice-cream increases as the cream whips. 
The flow of brine, therefore, should be regulated so that 
the cream will be at the temperature at which it will 
whip, for the maximum of time. If the freezer is run with 
the mix too warm, the cream will churn, and if the mix 
is too cold, the cream will not whip. 

In a tub and can freezer it is difficult to control the 
factors regulating the rate of freezing. When the mix 
begins to thicken and so turns hard, the speed of the 

* Washburn, R. M., "Principles and practice of ice cream mak- 
ing," Vt. Exp. Sta., Bui. 155, 1910. 



FREEZING PROCESS 139 

freezer is increased. This beats up the ice-cream and 
causes more swell. When the dasher and ice-cream are 
removed, the freezing-can will float in the brine, causing 
considerable difficulty when the next mix is ready to be 
frozen, since it will not easily go back in place. If the 
freezing-can cannot be centered in the tub, the cold brine 
should not be wasted, but should be dipped out and 
poured back after the can is in place. This saves con- 
siderable ice. In many plants, no attempt is made to 
center the can in the brine, this being dipped out as soon 
as the ice-cream is removed. 

One of the important factors in freezing is to obtain 
the proper swell. So far as this is concerned, the time to 
draw the ice-cream from the freezer can be told by the 
over-run tester. (See Chapter XIV.) 

111. " Over-run " or " swell." — It should be the aim 
of the person freezing the ice-cream to obtain the proper 
over-run with each freezer. A large number of factors 
affect the amount of swell, and the possible combinations 
of these must be known. If too much swell is obtained, 
the ice-cream will be very porous, light and fluffy, and 
have a grainy texture; if not swell enough, it will be very' 
heavy and soggy and may or may not be grainy in tex- 
ture. For the best results, a medium swell is to be desired. 
The factors affecting swell * may be divided into two 
general classes: kind and preparation of materials used, 
manner or method of freezing. 

* Washburn, R. M., " Principles and practice of ice-cream-mak- 
ing," Vt. Exp. Sta., Bui. 155, 1910; Baer, A. C, " Ice-cream making," 
Wis. Exp. Sta., Bui. 262, 1916; Mortensen, M., " Factors which in- 
fluence the yield and consistency of ice-cream," la. Exp. Sta., Bui. 
180, 1918; Ellenberger, H. B., " Swell in ice cream," Thesis, Grad- 
uate School, Cornell Univ., 1915. 



140 THE BOOK OF ICE-CREAM 

I. Kind and preparation of materials used. 

1. Age, viscosity, acidity, and fat-content of milk 

and cream. 

2. Size of fat globules in cream. 

3. Ageing of mix. 

— 4. Pasteurizing of milk and cream. 

5. Use of homogenizer. 

6. Use of emulsor. 

7. Methods of mixing. 
,.^-S-. Use of condensed mix. 

9. Amount of sugar. 

10. Different kinds of flavoring. 

11. Fillers and binders. 

12. Total solids in mix. 

The older the milk and cream and the more acidity 
they contain, the more viscous they will be. This is to 
be desired since it will whip more readily. For test for 
viscosity, see Chapter XIV. The more fat present in the 
milk and cream the more viscous they will be and the 
smaller the fat globules, the more the cream and milk 
will whip. It is commonly known that in order to obtain 
viscosity and swell, aged cream must be secured. Instead 
of ageing the milk and cream, some manufacturers age 
the whole mix. If only the former are aged and these 
should sour, they could be churned into butter. How- 
ever, if the sugar and flavoring are added to the mix and 
the whole aged and in the process become sour, the cream 
would not make good butter when churned. Therefore, 
there is danger of greater loss when the whole mix is aged. 
Pasteurization temporarily destroys the viscosity of the 
milk and cream and as a result pasteurized cream must 
be aged longer to restore the viscosity. The homogenizer 
and emulsor breaks the solids of the milk and cream into 



FREEZING PROCESS 141 

smaller particles. In some plants the whole mix is homog- 
enjzed_or_ emulsified before going to the freezer. This 
increases the viscosity and because of this and of the 
smaller particles, more swell is possible without sacrificing 
quality. With the emulsor, cream can be made from butter 
and skim-milk, but it lacks, the force of the homogenizer, 
and so cannot break up the solids as can the latter. Emulsi- 
fied cream is more viscous than raw cream of the same age. 

While mixing, care should be exercised not to churn 
the cream. If churning takes place, it reduces the solids 
and so the possible swell. By the use of condensed or 
powdered milk, the amount of total solids in the mix is 
increased. Condensed milk usually causes the mix to 
become more viscous. The amount of sugar is important 
only because of its bulk; the more sugar added, the more 
solids in the ice-cream. The swell is affected by the 
flavoring since some flavors add more bulk. 

Authorities disagree as to the effect of binders and 
fillers on swell. If some cause an increased swell, this is 
very slight. The total solids in the mix have a decided 
influence on the amount of swell that can be obtained 
without injury to the quality of the ice-cream; the more 
solids in the mix, the more swell. 

II. Manner or method of freezing. 

1. Speed of dasher in freezer. 

2. Temperature of mix entering the freezer. 
3.- Temperature of brine and rate of flow. 

4. Temperature of mix while whipping. 

5. Time of whipping. 

6. Total time to freeze. 

7. Temperature of ice-cream when drawn from 

freezer. 

8. The amount of mix in the freezer. 



142 THE BOOK OF ICE-CREAM 

The manufacturers of the different freezers have 
studied their machines and determined the speed at which 
they should run. The ice-cream-maker should see that 
the freezer runs at the speed indicated. 

The nearer the temperature of the mix to 40° F. when 
put into the freezer, the easiej; it is to obtain the swell. 

Mortensen * says "that a temperature of about 6° F. 
for the circulating brine would be the most desirable 
when using a 20 per cent raw cream. For pasteurized 
cream a temperature of from 8 to 10° F. gave the best 
results, while for emulsified cream about 10° F. and for 
homogenized cream 14° F. proved the most satisfac- 
tory." No record of the rate of flow of brine is re- 
corded. The temperature and flow of the brine should 
be such that the desired swell is obtained together with 
the quality. 

Washburn f shows that the mix whips at certain tem- 
peratures, usually from 32° F. to 29° F. The length of 
time of whipping has a decided influence on the quality 
of the ice-cream and the amount of swell. 

The total time to freeze has a noticeable effect on the 
quality of the ice-cream and the amount of swell. If 
frozen too quickly, swell will not be obtained and if too 
long, swell will be lost. 

Washburn { proves that the temperature at which the 
ice-cream is drawn from the freezer has a marked effect 
on the swell. If frozen too cold, the swell is lost. 

* Mortensen, M., " Factors which influence the yield and consist- 
ency of ice-cream," la. Exp. Sta., Bui. 180, 1918. 

t Washburn, R. M., "The principles and practice of ice-cream- 
making," Vt. Exp. Sta., Bui. 155, 1910. 

J Washburn, R. M., "The principles and practice of ice-cream- 
making," Vt. Exp. Sta., Bui. 155, 1910. 



FREEZING PROCESS 143 

According to Mortensen,* the amount of mix in the 
freezer influences the swell. For the best results, the 
freezer should be about half full. 

Certain combinations of the factors mentioned above 
will increase the swell, while certain ones will decrease it. 

To obtain swell: 

1. Have viscous milk and cream. 

2. Age the milk and cream or mix. 

3. If pasteurized milk and cream are used, they 

should be aged until viscous. 

4. The cream and milk or whole mix should be 

homogenized or emulsified. 

5. Condensed milk in the mix would aid in obtaining 

swell. 

6. The mix should contain at least 30 per cent of 

total solids. 

7. The dasher should run at the required speed. 

8. Mix should enter freezer as near 40° F. as possible. 

9. There should be a . supply of cold brine, from 

6° F. to 10° F. 

10. The cream should be whipped for a moderate 

time in the freezer. 

11. The mix should fill the freezer half full. 

12. It should require 12-20 minutes to freeze. 

13. The ice-cream should not be below 27° F. when 

drawn from the freezer. 

The converse of these conditions will cause a decrease 
in the amount of swell. 

112. Condition of ice-cream when removed from 
freezer. — ^When taken from the freezer, the ice-cream 
is in a semi-solid condition. It is soft enough to flow 

* Mortensen, M., " Factors which influence the yield and con- 
sistency of ice-cream," la. Exp. Sta., Bui. 180, 1918. 



144 THE BOOK OF ICE-CREAM 

from one container to another and yet hard enough to 
retain the incorporated air. In order to use the freezer 
over and over, the ice-cream is usually placed in pack- 
cans to harden. A parchment paper is put over the top 
of the can before going to hardening-room. The ice-cream 
can be drawn from brine freezers directly into the pack- 
cans. With the tub and can ice freezers, it is necessary 
to dip the ice-cream from the freezer into the pack-cans. 
This is more easily done if the dasher is first removed. 

113. Freezing sherbets and ices. — The foregoing state- 
ments apply to ice-cream and may or may not be applica- 
ble to sherbets and ices. Because of the higher percentage 
of sugar and water, the latter usually freeze more slowly. 
Any difference in procedure is noted under the receipt 
for sherbets and ices. 



CHAPTER XI 
HARDENING ICE-CREAM 

Ice-cream which is of good quahty up to this stage in 
the manufacturing process may be spoiled or the quahty 
impaired by improper hardening. The object, as its 
name indicates, is to harden the semi-frozen product after 
it is frozen in the freezer. During the time that the ice- 
cream is hardening, the flavors of the different ingredients 
blend to give the desired characteristic flavor. 

114. Methods of hardening. — The ice-cream may be 
hardened in the freezer, but this allows only one mix to 
be frozen and the machine cannot be used again until 
the product is consumed. This method is ordinarily 
followed with the small hand freezers. With the larger 
freezers, however, the ice-cream is hardened in pack- 
cans (Fig. 25) or bricks. (Fig. 58.) This allows the freezer 
to be used over and over. The ice-cream can be drawn 
directly from the brine freezer into the pack-cans or 
bricks; however, with the salt and ice freezer, the ice- 
cream must be dipped by hand. Various ladles or scoops 
have been devised for this purpose. (Fig. 53.) These are 
more or less rounded on the edge to scrape the sides of 
the freezing-can. 

The ice-cream in the pack-cans or bricks may be hard- 
ened in any one of several ways: packing in an ice and 
salt mixture, setting in cold brine, setting in a cold room 
called a hardening-room. The first two are not advisable 
for a large ice-cream plant because of the work and space 
required. 

145 



146 



THE BOOK OF ICE-CREAM 



115. Hardening in ice and salt mixture. — When the 
ice-cream is hardened in a salt and ice mixture, the cans 
are placed usually in a large plank box, Fig. 54, so that 
there will be a space of four to six inches between the 
cans and the box. The size of the box will be determined 
by the amount of ice-cream manufactured. If five-gallon 
cans are used, it is advisable to build the box in com- 
partments which will hold six. This will require a box 

26 inches wide by 32 
deep by 36 long, 
outside measurement, 
with a hinged cover 
for each compartment. 
The box should be 
made of two-inch 
matched lumber so 
that it will not leak. 
There should be a hole 
in the side near the 
bottom so the brine 
can be drawn off. Be- 
fore beginning to freeze, it is advisable partly to pack the 
cans in the box. A layer of four to six inches of cracked ice 
should be placed in the bottom of the box, then the cans 
placed in position and the box filled about two-thirds the 
height of the can with cracked ice. Some salt should be 
sprinkled on the ice and the box filled to the top of the 
cans with cracked ice. This cools the cans so that there 
will be no melting when the ice-cream is put in. The ice- 
cream may be poured directly from the freezer into the 
pack-cans or first it may be put into some container which 
is easier to handle and then poured from it into the pack- 
can. When all the cans in the compartment are full, 




Fig. 53.- 



-Different styles of transfer 
ladles or scoops. 



HARDENING ICE-CREAM 



147 



they should be covered to a depth of four to six inches 
with ice and salt. These may be mixed before putting in 





Fig. 54.— Plank box for hardening ice-cream in a salt and ice mix- 
ture. The cans are placed in perforated cylinders so that they 
may be changed and the ice will not fall in and fill the space. 

the box or they may be placed in alternate layers. The 
proportion of salt to ice for hardening is about one part 



148 THE BOOK OF ICE-CREAM 

of salt to eighteen or twenty parts of ice by weight. Most 
of the salt should be placed in the upper third of the ice, 
because as the ice melts the salt goes into solution and so 
is carried to the bottom of the box where it comes into 
contact with ice where there is little or no salt. For 
packing, a coarse salt is to be preferred as it dissolves 
more slowly. After standing overnight in the pack-cans, 
the ice-cream should be hard. It may be shipped out or 
held until wanted. If shipped the cans may be packed 
in tubs, observing the same precaution of placing the salt 
in the upper third of ice. Instead of packing in a tub, the 
cans may be put in a box or cabinet on the delivery 
wagon. If the ice-cream is to be held in the hardening- 
box, it should be repacked twice a day. This is done by 
jamming down the ice and salt. The cans should then 
be recovered with ice and salt. The brine which forms 
should be allowed to escape from time to time so that it 
will not run into the cans or cause them to float. The 
following figures on the amount of ice and salt used were 
obtained by the '' Ice-Cream Trade Journal." * They are 
the average of a number of plants: 

Average output of ice-cream per day, summer 395 gallons 

" " " " '' winter 43 " 

Amount of ice used per 100 gallons of ice-cream. . . . 1928 pounds 

for freezing 614 

for hardening and storage 914 

for shipping delivery or cabinets .... 400 

Amount of salt used per 100 gallons of ice-cream . . . 190 

for freezing 73 

for hardening and storage 82 

for shipping delivery or cabinets . ... 35 

116. The slush-box or brine-box method of harden- 
ing. — In this method, the pack-cans instead of being 
* "Ice-Cream Trade Journal," Vol. V, No. 6. 



HARDENING ICE-CREAM 149 

packed in iee and salt are placed in a box or tank of brine. 
This brine is usually cooled by means of a mechanical 
refrigerating system, and circulated with a pump. Great 
care must be exercised or the brine will get into the ice- 
cream. 

117. The hardening-room. — In the large ice-cream 
plants, a cold room is maintained in which the pack-cans 
are set to harden. This room is cooled by mechanical 
refrigeration and the temperature should be very near 
0° F. or below. There are three general types of harden- 
ing-rooms, depending on the location of the evaporating 
coils and the air circulation. 

118. The still-air type. — This type of hardening- 
room is used in the smaller ice-cream plants. The evapo- 
rating coils are placed directly in the hardening-room and 
usually arranged in such a way that shelves are formed 
with parts of the coils on which the cans of ice-cream are 
put to harden. (Fig. 55). 

119. The gravity-air type. — In this system the coils 
are placed in a bunker-room directly over the hardening- 
room and designed so the air will circulate in a natural 
manner. 

120. The forced-air type. — This system locates the 
eoils in a bunker-room usually, directly over the harden- 
ing-room, and the air is forced to circulate by means of 
a fan or blower. (Fig. 56). The forced-air system is con- 
sidered the most efficient. The effect is the same as the 
temperature of the air on the body. With the same 
temperature, the cold is more noticeable and more pene- 
trating on a windy day than when the air is still. The 
same is true in the hardening of the ice-cream. The 
objection to the still-air hardening-room is the longer 
time required to harden the product. The objection to 



150 



THE BOOK OF ICECREAM 




Fig. 55. — Still-air hardeningTroom showing evaporating coils forming 
shelves on which the pack-cans of ice-cream are placed to harden. 
Other evaporating coils may be seen on the sides and ceiling. 



HARDENING ICE-CREAM 151 

the forced-air room is the danger of losing too much 
refrigeration when the doors are opened unless the fan 
causing the air circulation is stopped before opening. 

121. Defrosting the coils.* — "One of the most trouble- 
some things to be contended with in ice-cream hardening- 
rooms, cooled by means of refrigerating machines, is the 
accumulation of frost or snow on the coils, and up to the 
present' time no thoroughly satisfactory method has been 
devised which will meet with success under all conditions, 
taking into consideration, method of operation, design 
of coils, and the like. 

"The most serious objection to this accumulation is 
the loss in efficiency, which may amount to as much as 
50 or 75 per cent, depending on the thickness of the coat- 
ing and the interference with the air circulation. The 
other objections are of minor importance and need not 
be considered here." 

1. Cooper system. 

The Cooper system consists of a trough perforated at 
the bottom and placed directly over each stack of coils, 
and in which are put lumps of chloride of calcium. This 
substance, on coming in contact with moisture in the 
air, will dissolve slowly and drip down over the coils, 
thereby keeping them practically free of frost at all times. 
; It may be asserted that this is not a defrosting device ; 
however, prevention is better than cure. 

This system can be applied to the first and second 
types of rooms, as in these cases the floor under the coils 
is made water-tight and arranged to catch the drip from 
the coils. It is not suitable for use in the third type, 
however, as the drippings would fall upon the cream-cans 

* Carpenter, M. R., "Defrosting of coils in hardening-rooms." 
"Ice-Cream Trade Journal," Vol. XI, No. 4. 



152 



THE BOOK OF ICE-CREAM 



and on the floor of the room. It is possible to catch these 
drippings and by boihng or evaporation recover the 
calcium, which can be used over again or in strengthening 
the brine in the tanks. 




Fig. 56. — Forced-air hardening-room. 



The objection to this system is the labor involved in 
placing it in the troughs, for usually the coils are close 
together and are in a room with little space around and 
over themlfor a man to work; also, the rooms being cold, 
it is a very uncomfortable task. It may be possible, in 



HARDENING ICE-CREAM 153 

designing rooms, to provide space in which to work, or 
to fill the cans outside the room and then place in posi- 
tion. 

2. Cold hrine drip system. 

This system consists of a means of spraying cold brine 
(calcium or salt) over the coils. Over each stack of coils 
is placed a trough, slotted or perforated pipe, similar to 
the water pipe or trough on atmospheric condensers. 
Brine from the main tank or circulating system is turned 
into the trough and allowed to drip over the coils either 
continuously or intermittently as may be required. 

In this system the brine must be very strong or it will 
freeze on the lower coils, especially if the frost is allowed 
to accumulate to any extent before defrosting, or unless 
the coils are out of commission entirely during the opera- 
tion. This brine is sometimes allowed to drain directly 
back into the brine tank, although this is poor policy as it 
weakens the brine and has a tendency to make it (in the 
case of calcium brine) acid, owing to its contact with the 
air. A better way, if it is possible to do so, is to drain it 
back into a tank, where it can be boiled and thus brought 
to its proper strength before returning to the main tank. 
This system has the advantage of being operated with 
nttle labor and under comfortable conditions, providing 
the controlling valves are placed outside the room and 
of easy access. In case the frost is allowed to accumulate 
to any extent, this system will not work as quickly as 
may be desired. One great advantage, however, is that 
it will not warm up the hardening-room, and if operated 
often and properly it will keep the coils free of frost and 
not require the room to be out of commission. This 
system is suitable for use in first and second types of 
rooms. 



154 THE BOOK OF ICE-CREAM 

3. Hot brine system. 

This is arranged the same way as the cold brine drip 
system as far as interior arrangement on coils is concerned, 
but instead of using brine from the main tank, a special 
tank with steam coil is provided and the brine is pumped 
into the trough in a hot condition and allowed to drain 
directly back into the tank. This system is quick in its 
results. A heavy deposit of frost can be removed in this 
way and it is easily operated. 

The principal objection is the great amount of moisture 
it will cause to be deposited on the walls and ceiling of 
the room. It also requires the room to be out of com- 
mission a short time while being operated. However, it 
does not seem to have much effect on the temperature 
after it is shut off. 

This method can also be made a cold brine system by 
boiling off after using, then letting it stand until it is cold 
before utilizing again. However, it will still deposit some 
moisture and it has been found best to keep the room out 
of commission while operating. Another tank with refrig- 
erating coil placed so as to cool this brine before using might 
be beneficial, although in this case it resolves itself into sys- 
tem No. 1. This can be applied to first and second types. 

4. Air blast system. 

In this system the air is so designed that the bunker- 
room can be shut off from the hardening-room and open- 
ings arranged so that the circulation fan can draw warm 
air from outside, blow it across the coils and discharge it 
at the opposite end. This is a very satisfactory and 
quick method, although it leaves some moisture deposited 
on the walls of the room and has a tendency to warm 
things up a little. This system, of course, needs a fan 
and is suitable for the first type only. 



HARDENING ICE-CREAM 155 

5. Hot gas system. 

This is a radical change from those systems considered, 
as it works from the inside out. The success of this system 
depends on the design of the coils, headers and connec- 
tions. The coils are arranged in such a way that they 
are, by opening and closing a few valves, converted into 
an ammonia condenser with the hot ammonia gas from 
the discharge of the compressor entering the top pipe of 
coils, and, as it is liquefied, running by gravity back to 
the ammonia receiver. In operating, it is necessary to 
have the room out of commission unless the coils can be 
arranged in independent batteries. 

This system can be applied to any type of room pro- 
vided the coils are properly designed and the receiver on 
a level below the lowest coil. Also, there must be enough 
additional refrigeration to enable the compressor to 
continue in operation in order to supply the hot gas. 

6. Warm liquid system. 

The coils, headers and piping are so arranged that the 
liquid ammonia on its way to other rooms can be passed 
through coils which are to be defrosted. It is self-evident 
that it is necessary to maintain the same pressure on 
these coils as obtains in the main liquid line, also that a 
considerable amount of ammonia must be expanding at 
other points in order to keep a quantity of liquid flowing 
through the coils. 

When conditions are right, this system is very satis- 
factory, as it can be operated with a minimum of labor 
and has the advantage of conserving all the energy previ- 
ously expended in freezing the ice on the coils. In apply- 
ing, special consideration must be given to the method 
by which the ammonia is fed into the coils. It is more 
easily applied to the flooded system, as in this case it is 



156 THE BOOK OF ICE-CREAM 

only necessary when defrosting is completed to cut off 
the flow of hot liquid, open the suction line from coils and 
allow the liquid remaining in the coils to expand or evapo- 
rate to accumulator, without danger of flooding over into 
the compressor. After this liquid is partly evaporated, 
the valve on the feed line from accumulator is opened, 
and the coils are again in full operating condition. 

In applying this system to direct expansion coils, care 
must be exercised to provide means either to drain the 
liquid back into the ammonia receiver before opening the 
outlet from coils into the main suction line, or to expand 
this liquid through other coils; otherwise, the liquid is 
Hable to reach the compressor with disastrous results. 

The application of this system should be attempted 
only by those thoroughly competent to consider all phases 
of the situation and if properly applied is one of the most 
efficient and satisfactory methods of defrosting yet de- 
vised. It can be applied to practically any type of room 
providing, as stated, the other conditions are suitable. 

It has been the writer's experience that the coils in 
forced-air circulating types give the most trouble, due to 
the heavy frost, partly from the very rapid accumulation 
and partly for the reason that these coils being out of 
sight are more hkely to be neglected, and after the ice 
has become very heavy it is exceedingly difficult to get it 
all off, without keeping the room out of use for a long time. 

The gravity system also gives some trouble, but is not 
affected quite so quickly as the forced-air type, owing 
partly to the design of the coils which necessitates greater 
space between pipes. The still-air type causes very little 
difficulty and some of these have been run a whole season 
without being defrosted and without having their effi- 
ciency materially reduced. 



HARDENING ICE-CREAM 157 

A large percentage of hardening-rooms have no arrange- 
ments for defrosting and as a result it is often necessary 
to shut down and remove the ice. All kinds of methods 
are used, such as scraping by hand, spraying with water 
by means of a hose, placing salamanders in the room or 
simply leaving the doors open and allowing the temper- 
ature of the room to rise to such a point that the frost 
will melt. 

122. Time required for hardening.— The time neces- 
sary for hardening varies, but usually .twelve hours is 
sufficient. The time depends on the rate of removal of 
heat or the amount of cold supplied and the insulation. 
The refrigerating boxes should be well insulated. This 
is especially necessary because of the great difference 
between the temperature of the hardening-room and that 
of the surrounding atmosphere. Undoubtedly cork makes 
the best insulation. The thickness varies, but it should 
be at least six or eight inches thick. Cork should be kept 
dry or it is not a good insulator. When the ice-cream 
becomes hard, it should be held at a low enough temper- 
ature so that it will not soften or melt. After hardening, 
if the ice-cream melts or sdftens it is liable to cause the 
separation of the ice crystals and so result in a grainy 
textured product. If it becomes soft, the fat is likely to 
rise unless the cream has been homogenized. Ice-cream 
should not be held in the hardening-room for more than 
seven days. 

When an ice and salt mixture is employed to harden 
-the ice-cream, the rate of hardening is determined by the 
amount of salt used. The coarse, slow dissolving salt is 
to be preferred for hardening. 

123. Effect of hardening on quality. — The two quali- 
ties of ice-cream affected by hardening are the flavor and 



158 



THE BOOK OF ICE-CREAM 



body and texture. While hardening, the flavors of the 
different materials used blend to give the desired charac- 
teristic flavor. Some flavors, especially vanilla, will 
freeze out while hardening. The body and texture are 
affected only through neglect. If the paek-cans are 
allowed to stand after they are filled, before being placed 
in the hardening-room, some of the ice-cream next to the 
sides and bottom will melt, causing a grainy or icy texture. 
The same may occur if there is water in the bottom of the 
pack-cans when the ice-cream is put in. 

124. Fancy molded ice-cream. — There are two kinds 

of fancy molded ice- 
cream, bricks and 
molds to represent 
various objects. The 
ice-cream is the same 
with the exception of 
the form in which it 
is hardened. Some- 
times a little more 
stabilizer is used to make the cream more firm. The 
brick offers many possible combinations. Each kind of 
ice-cream is put into the brick in a layer. Each layer 
is leveled with a brick trowel. This trowel is square 
on the end and just the width of the brick. (Fig. 57.) 
A different flavor and color of ice-cream forms each 
layer. In some cases the center is a sherbet or pudding. 
Mortensen suggests a center layer of solid frozen fruit and 
calls such ice-cream Aufait. The size of the brick varies 
from a pint to several quarts. (Fig. 58.) It is the custom- 
ary practice to use sectional bricks (Fig. 58) which are 
the exact size to hold six to eight quart bricks. These 
may have a single or double lid. When hard, the ice- 




FiG. 57. — Brick ice-cream trowels. 
Straight and bent handles. 



HARDENING ICE-CREAM 159 

cream is taken from the sectional brick and cut into 
either quart or pint sizes. In a large factory, a special 
hardening-room is employed for brick ice-cream, which 
is kept as near 0° F. as possible. (Fig. 59.) The contents 



Fig. 58. — Quart and sectional brick molds. The sectional bricks 

hold several quarts. 

are taken from tbe brick mold by applying cold water 
until sufficient frost has been drawn from the mold to 
allow the ice-cream to slide out. When a large number is 
made, a special brick-cutting machine may be used. This 
will cut the bricks much faster and more uniform in size 
than by hand. Sometimes if a knife is run around the 



160 



THE BOOK OF ICE-CREAM 



sides of the brick it will help loosen the ice-cream. Care 
should be taken not to melt the ice-cream too much. 
In some instances the bricks are packed in square, in- 
stead of round pack-cans for delivery. In this case a 
large number of bricks would be delivered to the same 
place. The bricks are wrapped in parchment paper, 
put into paper cartons and packed in ice and salt for 
delivery. 




Fig. 59. — Brick hardening-room. 

By means of a specially devised mold or brick known 
as a center mold (Fig. 60), any letter, figure or form of 
object may be made in the center of the ice-cream. To 
accomplish this, two different colored ice-creams must 
be used. The form is produced by having one cover of 
the mold with a tube of the desired shape to form the 
center figure. The space around the tube is filled with 
one colored ice-cream and the tube or center with the 
color desired in the center. When the brick is sliced, 
this design is in the center of each piece of ice- 
cream. 



HARDENING ICE-CREAM 



161 



By means of special molds, ice-cream may be hardened 
to represent almost any object. (Fig. 61.) These molds 




Fig. 61. — Individual ice-cream molds and ice cave for packing 

molds. 

are hinged pewter metal. They vary in size from one or 
two quarts to an individual service. These cannot be 



162 THE BOOK OF ICE-CREAM 

packed in an ordinary pack-can without jammingo They 
usually are wrapped separately with waxed paper and 
hardened and delivered in an ice cave (Fig. 61), which 
consists either of a round or square pack-can into which 
a frame with shelves fits. The molds of ice-cream are 
placed on these shelves. 



CHAPTER XII 
JUDGING AND DEFECTS OF ICE-CREAM 

The judging of ice-cream is the comparing of one 
product with another or of the one in question with the 
ideal. In order to make this comparison more simple, 
a score-card has been devised. This gives a numerical 
value to each of the characteristics of the material to be 
judged and makes comparisons easy. The judge should 
be familiar with the various qualities and defects of the 
material under his inspection. 

125. Score-cards. — Several score-cards * have been 
suggested for ice-cream, but no one is in universal use as 
is the case with both butter and cheese. 

In the New York State College of Agriculture at Cor- 
nell University, two score-cards are used. They are as 
follows: 



Score-card No. 1 




Score-card No. 2 


Flavor 


45 


Flavor 40 


Body and texture 


35 


Body and texture 25 


Richness 


10 


Bacterial count 15 


Appearance 


5 


Richness 10 


Package 


5 


Appearance 5 
Package 5 



Total 100 Total 100 

* Baer, A. C, "Ice-cream-making," Wis. Exp. Sta., Bui. 262, 1916; 
Mortensen, M., "Classification of ice-creams and related frozen prod- 
ucts," la. Exp. Sta., Bui. 123, 1911; Washburn, R. M., "Principles 
and practice of ice-cream-making," Vt. Exp. Sta., Bui. 155, 1910; 
Frandsen, J. H,, and Markham, E. A., "The manufacture of ice- 
cream and ices," Orange Judd Company, 1915. 

163 



164 THE BOOK OF ICE-CREAM 

These score-cards consider the same characteristics 
except that No. 2 includes the bacterial count. Naturally 
the inclusion of another characteristic changes the nu- 
merical value of the others. Score-card No. 1 is for use 
only when there is not time to make a bacterial count, 
such as for laboratory work. When an exact comparison 
is desired, the bacterial count should be made. If un- 
desirable or large numbers of organisms are present, they 
affect usually the flavor and body and texture, although 
this is not always true. For this reason, the numerical 
value given to bacterial count has been taken from flavor 
and body and texture. 

126. Explanation of characteristics mentioned in score- 
card. — If the ice-cream is to receive a perfect score, 
the characteristics should be as defined. If not, the ice- 
cream is defective and the score should be cut. 

Flavor. — The ice-cream should have a pronounced 
flavor which will blend with that of the cream to give a 
clean, desirable typical flavor. 

Body and texture. — The body should be firm and mellow. 
It should not be tough or rubbery, neither soft or mushy. 
The texture should be smooth and velvety and entirely 
free from graininess and lumpiness. 

Richness. — If the ice-cream meets the legal require- 
ments, it should be given a perfect score. If it falls below, 
it should be scored zero. 

Appearance. — The ice-cream should have an attractive 
appearance and be of the characteristic uniform color. 

Package. — The package should be neat and clean and, 
if for long shipment, some provision should be made to 
protect the ice on top of the packing-tub. 

Bacterial count. — An ice-cream which has a count of 
20,000 should be considered perfect. For each increase 



JUDGING AND DEFECTS OF ICE-CREAM 165 

of 20,000 above this, one point should be deducted from 
the score. 

If a number of samples is to be scored, it is the usual 
custom to examine several to gain an idea of how the 
quahty runs. This is called establishing a key or stand- 
ard. When this has been done, all the samples can be 
scored and the best will not be rated too high nor the 
poorest too low. 

127. Defects in ice-cream. — It is almost impossible 
to make an ice-cream which does not have some defect. 
These can be discussed best under the characteristics as 
given in the score-card. 

128. Defects in flavor of ice-cream are largely due to 
objectionable flavors in the materials employed, or to 
the use of too much or too little of certain ingredients. 

Some of the common causes are: 

1. Use of cream of bad flavor. 

2. Use of cheap flavoring extracts. 

3. Use of too little or too much sugar. 

4. Use of materials which do not give the character- 

istic flavor. 

5. Disagreeable. flavor due to use of poor fruits. 

6. Lack of flavor due to use of too small an amount 

of flavoring materials. 

7. Too pronounced a flavor or not pronounced 

enough. 

8. Condensed milk flavor. 

9. Salty ice-cream. 

10. Gelatine or gum tragacanth flavor. 
. Of the ten causes mentioned all but number one are 
within the control of the ice-cream manufacturer. How- 
ever, the flavor of the cream is a very vital question and 
the one usually causing the greatest difficulty. 



166 THE BOOK OF ICE-CREAM 

129. Defects in body and texture. — The texture refers 
to the molecular structure. As the ice-cream is an emul- 
sion of materials of varying specific gravities^ it is difficult 
always to get these different ingredients to mix in the 
same manner. The greatest defect in the texture of 
the ice-cream is graininess. This may be caused by the 
incorporation of too much air or the separation of the 
water crystals. After the ice-cream has been transferred 
from the freezer to the pack-cans, the latter should be 
placed at once in cold surroundings; if not, the cream 
around the outside and bottom of the can will melt and 
on being hardened will be grainy, due to the melting and 
separation of the water crystals. Graininess may be due 
to a lack of binder or sometimes to the crystallization of 
the sugar in the condensed milk. 

The body of the ice-cream refers to the structure as a 
whole. The common defects in body are hard, brittle, 
soft or watery. In order to obtain an ideal body, the 
ice-cream must contain a certain amount of milk-fat and 
other solids; also this cream must be frozen properly. 
If the ice-cream lacks solids, the body is very likely to be 
soft or watery. The age of the cream, whether or not it 
has been pasteurized, and method of freezing, have a 
decided effect on the body. 

Sometimes in freezing the fat becomes churned; this 
results in chunks of fat in the ice-cream. It is caused by 
the freezer running too fast or by putting the cream into 
the freezer too warm. 

The following summary of two bulletins gives the 
effect of solids on the smoothness and keeping qualities 
of ice-cream and the effect of binders on the melting 
and hardness. These directly affect the body and 
texture. 



JUDGING AND DEFECTS OF ICE-CREAM 167 

Effect of solids on smoothness and keeping quality of 
ice-cream: * 

''1. Smoothness and keeping quality or stability of 
texture of ice-cream are closely associated. 

"2. Smoothness depends upon the amount and fine- 
ness of division of solids present other than those in true 
solution, within limits, that is, the smoothness depends 
upon the size and distribution of ice crystals which in 
turn depend upon the number and nearness together of 
minute sohd particles which interfere with crystallization 
and reduce the size of the ice crystal. 

''3. Colloidal solutions of solids other than fat are 
best adapted to ice-cream-making. The finer the division 
the better. 

"4. The finer the emulsion of the fats the better the 
homogenizer has its application in this respect. 

"5. The keeping qualities of ice cream depend upon 
the stabihty of the mix. That is, the keeping qualities 
of ice cream made from a given mixture will depend upon 
the disposition of the solids in that mixture to separate 
from the liquid, which in turn depends upon the fine- 
ness of division of the solids. The finer the division, the 
better the keeping qualities up to the point at which the 
solid merges into a true solution." 

Effect of binders on the melting and hardness of ice- 
cream: t 

"Plain ice-cream. — In plain ice-cream (control) as the 
per cent of fat increases the cream becomes softer. A 

*Brainard, W. K., "Smoothness and keeping qualities in ice- 
cream as affected by solids," Va. Exp. Sta., Tech. Bui. 7, 1915. 

t Holdaway, C. W., and R. R. Reynolds, "Effect of binders upon 
the melting and hardness of ice-crean," Va. Exp. Sta., Bui. 211, 
1916. 



168 THE BOOK OF ICE-CREAM 

medium amount of butter fat, combined with other mate- 
rial than milk solids, produces a stiff cream. When too 
much fat is present whipping takes place, producing a 
cream that is soft and fluffy in appearance. Ice-cream 
made from eight per cent cream is no harder than from 
nineteen per cent cream, while thirty per cent plain cream 
is much softer than eight per cent or nineteen per cent 
cream. In plain ice-cream the presence of fat increases the 
power to resist melting. This resistance is most noticeable 
between the melting of the eight per cent and nineteen 
per cent cream. Thirty per cent cream shows the power 
to resist melting to a less degree. 

^^ Cream containing gelatine. — Gelatine in a large or 
small quantity produces similar effects, depending upon 
the richness of the cream used. The power to withstand 
pressure and the melting resistance increases as the 
amount of gelatine increases, when compared with the 
control ice-cream with a similar fat content. The hardest 
and most heat resisting ice-cream is produced with a 
medium per cent of fat and a large amount of gelatine. 
With gelatine, the presence of fat seems to be essential to 
produce hardness and melting resistance until a point is 
reached where whipping affects the texture. After whip- 
ping begins the incorporated air reduces the hardness and 
melting resistance. Ice-cream containing one ounce of 
gelatine per gallon has more the appearance of pudding 
than ice-cream. Four ounces of gelatine gives about the 
same hardness as four ounces of cornstarch, but it is much 
better, producing a smoother cream which is more stable 
under ordinary conditions. 

^^ Cream containing gum tragacanth. — Gum tragacanth 
with a low per cent of fat produces an ice-cream that is 
slightly harder, with slightly more power to resist heat 



JUDGING AND DEFECTS OF ICE-CREAM 169 

than plain ice-cream. As the per cent of fat is increased 
with this filler, the power to resist pressure and heat de- 
creases, falling below plain cream, showing that gum 
tragacanth acts as a filler and not as a binder. Its most 
noticeable effects are on the texture of the ice-cream, be- 
cause of the nature of the gum, is to impart a smoothness 
which becomes sliminess when large quantities are used. 

^^ Cream containing cornstarch. — When cornstarch is used 
as a filler a slight increase in hardness and melting re- 
sistance is noticeable with nineteen per cent when com- 
pared with eight per cent, ice-cream. Also it produces an 
ice-cream that has more resistance to heat than plain ice- 
cream of the same per cent fat. When used as a filler it 
compares favorably with a similar amount of gelatine but 
the starch ice-cream is more granular than the gelatine, 
while gum tragacanth produces a smooth soft cream. '^ 

130. Defects in richness. — The only defect in richness 
is a lack of fat and sohds not fat. The ice-cream should 
meet the legal standards; if not it is defective. 

131. Defects in appearance. — Many times the ice- 
cream does not have an attractive appearance. It may 
be rough, grainy and coarse, or partly melted. Often it 
will melt on the outside and run while the inside will be 
very hard. The ideal ice-cream is one which will have the 
same degree of softness throughout. The color is not 
always characteristic as the fruit may not be distributed 
uniformly. 

132. Defects in package. — Anything which detracts 
from the neatness of the package is a defect. Badly 
dented or rusted cans are not attractive. The tubs may 
not be clean or neatly painted or lettered. The parch- 
ment paper circles being omitted from the top of the can 
constitutes a defect. 



CHAPTER XIII 
BACTERIA IN RELATION TO ICE-CREAM 

Much might be written regarding the factors affecting 
the growth of bacteria, the preparation of the media, the 
incubating temperature, the counting; this is all discussed 
in the various text-books on bacteriology. Here only the 
relation of bacteria to ice-cream will be considered. 

It is commonly recognized that ice-cream contains 
large numbers of bacteria. The table No. VI * on page 171 
shows the average bacterial count of ice-cream and the 
highest and lowest counts in various cities and at different 
times in the same city. 

This table indicates that ice-cream made in different sec- 
tions of the United States has some extremely high counts 
and the average is comparatively high when one considers 
the count of milk and cream produced under clean condi- 
tions. The redeeming feature is that ice-cream can be 
produced with low bacterial count. This shows the need 
of a bacterial as well as chemical standard. 

133. Sources of bacteria in ice-cream. — :There are two 
sources of bacteria in ice-cream, the materials employed 
and the utensils which come in contact with the ice-cream. 
The latter source is entirely under the control of the 
manufacturer. If materials used have a low bacterial 
count, there is no reason why the ice-cream should not 
be low in bacteria. If this is the case and the ice-cream 

* Hammar, B. W., "Bacteria and ice cream," la. Exp. Sta., Bui. 
134, 1912, 

170 



BACTERIA IN RELATION TO ICE-CREAM 171 



t-5 



ooooooooo 

^, OOOOOOOOQ 

;s o"o"i>-'~o'^o"o~o"o'^o'" 



> 

< 






o 

c3 

PQ 
o 

03 






QOQOOOOOO 
COOOOOOQO 

^ so <^^P.<^ o o o o o^o^ 
•^ o o^o^o^o^o^o^o^o^o 

05 crLf:rio"cro"o"<^ c^ 

t^iOO<NOOOCOI>. 

T-H CO T— I T-l (M O 






rt -cS lO 



5- 

CO 



■O CO 

^co 
<^co 

o 



O i-H '^ o o 
O t^ CO o o 
O^CO^i-H^O o 

o'^f^rofr-To'^ 

O 1— I O o o 
o^cq^cq^T-fH oo 

co'^co'cD^Lo'T-r 
(M (M T-i tH 



g^^ 



;^ 



S Oi LO CO oo o 
S ^ CO CO 00 oo 
I <^« CO 

5^ 



' o '^ t^ J^ 
' -^ O Q O 



oo 



O lO 

O Oi 



CO O (M 

(M T-l 7-1 



"to 



§.lO CO CO Oi O rH 
^O O O O ^ rH 

O^ O'i Oi <3:> (^ (^ 






o 



1— I 

I 

T-\ 1— I 
1—1 T—t 

05 Oi 



o3 

m IX) 



l^h'ojJ^ooo'^p - 



172 THE BOOK OF ICE-CREAM 

has a high count, it would indicate that the maker was 
careless and the utensils dirty. 

EUenberger * found the minimum and maximum num- 
ber of bacteria in the materials used in the mix as given in 
Table VII: 

Table VII 

The Minimum and Maximum Bacterial Content of the In- 
gredients used in the Mix 

Minimum Maximum 

Standard cream per c. c. . 1,150 37,600,000 

Condensed milk per c. c 31,500 59,800,000 

Sugar per gram 20 255 

Gelatine 48 891 

Flavoring vanilla 10 321 

The important fact brought out by the above table is 
that the milk products are the source of most of the 
bacteria in the ice-cream. This emphasizes the need of 
dairy products manufactured and marketed under the 
most cleanly conditions. The ice-cream-maker in most 
cases has little control over these factors. For the produc- 
tion and handling of milk, see Chapter 11. The numbers 
of bacteria may be reduced materially by pasteurization.! 
This destroys the viscosity so that milk or cream that has 
been aged and then pasteurized must be aged again to 
regain it. There is great danger while ageing either 
pasteurized or raw cream of a material increase in the 
numbers of bacteria. Great pains must be taken to cool 

* EUenberger, H. B., "A study of the bacterial growth in ice- 
cream," Thesis, Cornell Univ., 1917. ' . 

t EUenberger, H. B., "A study of the bacterial growth in ice- 
cream," Thesis, Cornell Univ., 1917; Hammar, B. W., "Bacteria and 
ice-cream," la. Exp. Sta., Bui. 134, 1912; Hammar, B. W., and Goss, 
E. F., "Bacteria and ice-cream," Part II, la. Exp. Sta., Bui. 174, 
1917. 



BACTERIA IN RELATION TO ICE-CREAM 173 

and hold or age it at a low enough temperature so that the 
organisms will not develop. If this is not done, the result 
would be practically the same as if it had not been pas- 
teurized, so far as numbers of organisms are concerned. 

Hanmiar gives the count of different samples of gelatine 
as follows: 

Table VIII 
Bacterial Count of Samples of Gelatine 

Bacteria in 1 c. c. 
Bacteria per of ice-cream due 

Sample No. gram to gelatine 

1 113,000,000 565,000 

2 14,000,000 70,000 

3 35 0.2 

4 4,200 21 

5 85,000 425 

This table shows the need of testing to make sure that 
the supply of gelatine is low in number of bacteria. Usually 
in the better or more expensive grades, the bacterial con- 
tent is lower, but this is not necessarily true. The method 
of preparation has much influence on the bacterial 
content of ice-cream. (See Chapter IV.) 

Sugar contains very few organisms. The greatest danger 
is that dirt may get into the sugar due either to exposure or 
sifting through the cloth sacks. 

The flavoring materials may have a decided influence on 
the bacterial content of the ice-cream. Vanilla contains 
very few organisms, but such flavors as fruits may have 
large numbers of bacteria, especially if they are not sound. 

Hammer * reaches the following conclusions regarding 
the bacterial content of the materials used in the manu- 
facture of the ice-cream : 

* Hammar, B. W., " Bacteria and ice-cream," la. Exp. Sta., Bui. 
134, 1912. 



174 THE BOOK OF ICE-CREAM 

1. The cream unless pasteurized is the greatest source 
of the bacteria in ice-cream. 

2. After pasteurization cream can be stored at 0° C. 
for several days with no important increase in the number 
of bacteria developing at 37° C. on agar. 

3. The bacterial content of gelatine is very valuable and 
some probably add large numbers of bacteria to ice-cream 
in which they are used. 

4. The vanilla extract plays a very small part in de- 
taining the bacterial content of ice-cream. 

5. The sugar is comparatively unimportant as regards 
the number of bacteria in the ice-cream made with it, if it 
has been properly protected from dirt. 

All the utensils, unless clean, may be a source of con- 
tamination to the ice-cream. When machines are selected, 
the ease of cleaning should not be overlooked. All seams 
should be flushed with solder. This leaves no crevices in 
which bacteria and dirt can lodge, and makes cleaning 
easy. The cleaning of the freezer should receive special 
attention. 

134. The effect of freezing and hardening on the bac- 
terial count. — Authorities agree that there is an increase 
in the number of organisms in ice-cream during the 
freezing process, as determined by the plate method. 
This may be accounted for by the agitation in the freezer 
breaking up the clusters of bacteria. This cluster would 
give only one colony on a plate, but after being broken up 
might result in several colonies. This is not a real increase 
in the number of bacteria. The same holds true with 
other machines, such as the clarifier.* 

* Hammar, B. W., " Studies on the clarification of milk," la. 
Exp. Sta., Res. Bui. 28, 1916; Mclnerney, T. J., "Clarification of 
milk," N. Y. Cornell Exp. Sta., Bui. 389, 1917. 



BACTERIA IN RELATION TO ICE-CREAM 175 

Ellenberger found that there were no radical changes in 
the total number, of bacteria in ice-cream during harden- 
ing. There seems to be a tendency toward a slight de- 
crease in the first two or three days with a more noticeable 
increase and corresponding decrease again between the 
sixth and twentieth days, after which there is only a very 
gradual falling off in numbers. The lower temperatures 
may have a destructive effect on some types of organisms. 
There may be a reorganization with the survival of the 
fittest. 

135. Types of organisms in ice-cream. — The bac- 
terial flora of ice-cream in summer and winter was studied 
by Ayers and Johnson.* They divided the samples into 
summer and winter and the bacteria into groups by the 
milk-tube method of differentiation. 



Table IX 

Showing the Groups of Organisms and the Percentage in Each 

Group 

28 Winter 
samples 
per cent 
.30.84 
.38.03 
. 4.81 
. 5.42 
.20.90 



71 Summer 
samples 
per cent 

Acid-coagulating group 49 . 82 

Acid-forming group 20 . 72 

Inert group 13 . 98 

Alkali-forming group 1 . 86 

Peptonizing group 13 . 62 



136. The total-acid groups. — ''As seen in Table No. 
IX of the average bacterial flora of summer ice-cream 
70.54 per cent is made up of the total group of acid- 
forming bacteria, and during the winter 68.87 per cent. 
While using the milk-tube method of differentiation the 

* Ayers, S. H., and Johnson, W. T., Jr., "A bacterial study of ice- 
cream," U. S. Dept. Agr., Bui, 303, 1915. 



176 THE BOOK OF ICE-CREAM 

reactions of the litmus milk tubes are recorded after 2, 5 
and 14 days, and the total acid-forming group is composed 
of those bacteria which produce acid in litmus milk during 
the 14 days' incubation. Those bacteria which form acid 
and peptonize the milk are included in the peptonizing 
group. The total-acid group can be further divided into 
those which produce acid and coagulate the milk and those 
which simply form acid within 14 days. Since the reaction 
is recorded after 2, 5, and 14 days, the rapidity of the 
growth of the acid-forming bacteria can be determined, 
and this serves as an additional means of separating the 
group. In Table No. X the percentages of the acid- 
coagulating and the simple acid-forming groups of bac- 
teria are shown, based on the 2, 5 and 14 day reaction in 
litmus milk." 

Table X 

Changes in the Percentage of the Total-acid Group of Bacteria 
in Ice-cream when Determined by Litmus-milk Reactions after 
Various Lengths of Incubation 

Per cent reacting after 
incubation for 
Bacterial group 2 days 5 days IJf. days 

per cent per cent per cent 
Averages of 71 summer samples: 

Acid-coagulating 26.31. . . .41.52. . . .49.82 

Acid-forming 35.43. . . .25.58. . . .20.72 

Average of 28 winter samples: 

Acid-coagulating 8.20 25.02 30.84 

Acid-forming 44.51 41.30 38.03 

"An examination of Table No. X shows that among 
the summer samples 49.82 per cent of the bacteria pro- 
duced acid and coagulated the milk after 14 days. After 
2 days 26r31 per cent produced this reaction. This shows 
that a little more than half, or 52.81 per cent of the bacteria 



BACTERIA IN RELATION TO ICE-CREAM 177 

which were in the ice-cream produced the reaction within 
48 hours. The remaining 47.19 per cent coagulated milk 
more slowly and may represent a different variety of acid- 
forming bacteria. Turning again to the table and con- 
sidering the acid-coagulating group of the winter series, 
it will be seen that of the 30.84 per cent which produced 
the reaction only 8.20 per cent produced acid and coag- 
ulated milk in 2 days. Therefore only 26.69 per cent of the 
acid coagulating group of the winter samples were active 
enough to produce the reaction in 48 hours, while 52.81 per 
cent of this group in the summer samples brought about 
the change in 2 days. 

''There is little to be said regarding the acid-forming 
bacteria which simply produce acid. Many of them grow 
slowly and do not show an acid reaction for several days in 
litmus milk. The milk-tube method furnishes a means of 
determining the difference in the rapidity with which the 
bacteria produce acid. As may be seen in Table No. X the 
percentage of the acid-forming group of bacteria was 
highest when determined by the 2-day reactions and 
lowest when based on the 5 and 14 days' reactions. This is 
explained by the fact that many bacteria have simply 
formed acid after two days in litmus milk and later may 
coagulate or peptonize the milk, and are therefore thrown 
into another group." 

137. The inert group. — "The inert group of bacteria in 
ice-cream comprises those which produce no change in lit- 
mus milk during the 14 days' incubation at 30° C (86° F.). 
By this method of grouping there are, of course, included 
in the inert group those cultures which fail to grow in 
milk and tubes of litmus milk, and which would also be 
included even though the lack of growth were caused by 
failure to inoculate the tubes properly. However, this 



178 THE BOOK OF ICE-CREAM 

last possibility is small. The inert group is of little in- 
terest, on the whole, since the bacteria produce no apparent 
change in milk, and in all probability the same is true of 
ice-cream.'' 

138. The alkali group. — "The alkali-forming group of 
bacteria is made up of organisms capable of producing an 
alkaline reaction and no other apparent change in litmus 
milk during the 14 days' incubation at 30°C (86°F) . This 
group does not include bacteria which produce an alkaline 
reaction together with visible signs of peptonization. 
While there are in the literature references which deal 
with types of alkali-forming bacteria, this group has rarely, 
if ever, been considered when the flora of milk has been 
under discussion. The authors in some previous work 
on bacteria in milk showed that considerable numbers of 
this group were present in milk. In a later piece of work 
we have shown the numbers of this type of bacteria in 
milk, together with some of the cultural reactions of the 
alkali-forming bacteria. These bacteria, however, give 
very few positive reactions with the usual cultural media, 
and it is impossible to give much information regarding 
this group. A detailed bacteriological and chemical 
study of these organisms is under way in the research 
laboratories of the Dairy Division. 

"It will be seen from Table XI that during the summer 
series of ice cream samples the average sample contained 
1.86 per cent of the alkali group of bacteria, and during 
the winter series 5.42 per cent. In general, the alkaline 
reaction is not noticeable until after four or five days' 
incubation in litmus milk. Occasionally, however, the 
reaction is in evidence in 48 hours. This group percentage 
for the summer season was 1.86 after 14 days and only 
0.15 per cent based on the 2-day reaction. Therefore, 



BACTERIA IN RELATION TO ICE-CREAM 179 

only 8.06 per cent of the bacteria of the alkali group pro- 
duce an alkaUne reaction within 48 hours. Among the 
samples collected during the winter season only 3.13 per 
cent of the bacteria of this group were capable of producing 
the reaction within two days. Whether this indicates a 
different variety of organism can not be said with assur- 



ance." 



Table XI 



Changes in the Percentage of the Alkali Group of Bacteria in 
Ice-cream when Determined by Litmus-milk Reactions after 
Various Lengths of Incubation 

Per cent reacting after 
incubating for 
Alkali group 2 days 5 days U days 

per cent per cent per cent 

Average of 71 summer samples . 15 ..... 1 . 03 1 . 86 

Average of 28 winter samples 17 4.00 5.42 

''At present we are unable to state the significance of 
this group of bacteria in milk and ice-cream, but it is 
evident that they are not present in ice-cream in large 
numbers, as are the bacteria of other groups. 

''Alkali-forming bacteria were not found in each sample 
examined, but this does not prove that there were none 
present in the ice-cream. Since these organisms are 
present in small numbers compared to the rest of the 
, bacteria, it is not surprising that none should be found on 
plates in which the dilution had to be high in order to take 
care of the large total number of organisms." 

139. The peptonizing group. — "The peptonizing group 
is probably the most interesting if not the most important 
group of bacteria in ice-cream. This group consists of 
what are commonly known as the putrefactive bacteria; 
that is to say, they attack primarily the proteins, decom- 
posing them into less complex organic bodies. Bacteria of 



180 THE BOOK OF ICE-CREAM 

this class are usually considered undesirable in articles of 
food, and it is to them that intestinal troubles are some- 
times attributed, perhaps with or without justification. 
Whatever their true effect is will not be discussed in this 
paper, but because bacteria of this group are looked upon 
with suspicion it is therefore of great importance. 

''Among this group there are a large number of different 
types of organisms. Many rapidly peptonize the casein of 
milk and render milk alkaline or slightly acid, while others 
first attack the lactose and only produce a slight pep- 
tonization after several days' growth. From the milk- 
tube method of differentiation of the bacterial groups it 
was possible to gain some information as to the extent of 
these different classes of peptonizers. In Table No. XII 
are shown the average percentages of the peptonizing 
group in summer and winter samples of ice cream. Based 
on the 14-day reaction among the summer samples, 13.62 
per cent of the bacteria belonged to the peptonizing 
group. According to the 2-day reaction, there were 
5.93 per cent. Therefore 43.54 per cent of the peptonizing 
bacteria were sufficiently active! to produce a peptonization 
within two days. Among the winter samples 34.06 per 
cent of the peptonizing bacteria were sufficiently active to 
peptonize milk within 48 hours. These active peptonizing 
bacteria are more important than the slower-acting^ 
varieties, since their peptonizing action is usually more 
complete than that of the latter-named varieties, and if 
any harm is produced by this group, they are most likely 
to be the organisms concerned." 



BACTERIA IN RELATION TO ICE-CREAM 181 

Table XII 

Changes in the Percentage of the Peptonizing Group of Bacteria 
in Ice-cream when Determined by Litmus-milk Reactions after 
Various Lengths of Incubation 

Per cent reacting after 
incubation for 
Peptonizing group 2 days 5 days I4. days 

per cent per cent per cent 

Average of 71 summer samples 5 . 93 9 . 76 .... 13 . 62 

Average of 28 winter samples 7 . 12 .... 13 . 58 20 . 90 

140. Colon bacilli in ice-cream. — Since the presence of 
colon bacilli has been understood in water analysis to 
indicate fecal contamination, many investigators and 
boards of health apply the same tests to milk and nat- 
urally then to ice-cream with the same idea. In water 
analysis, lactose-bile fermentation tubes are employed for 
the examination for colon bacilli. By using different 
dilutions, the maximum number of gas-forming bacteria 
in a given amount of water may be determined. This 
preliminary test has to be followed by confirmatory ones 
in which cultures are isolated and their characteristics 
studied in order to prove the presence of colon bacilli. 
Ayers and Johnson used this method to some extent but 
endeavored to prepare a synthetic medium which would 
restrict the growth of the larger number of bacteria in ice- 
cream and at the same time would allow colon bacilli to 
develop and produce characteristic reactions. Ice-cream 
contained a much larger number of gas-forming organisms 
in the summer season. A large number of media were used 
in an attempt to devise a suitable medium for the detec- 
tion of Bacillus CoH in ice-cream and the results show that 
there is no entirely satisfactory method known at present. 
141. Difficulties in studying the bacteriology of ice- 
cream. — ^As has already been pointed out, one of the great- 



182 THE BOOK OF ICE-CREAM 

est difficulties in studying the bacteriology of ice-cream is 
the lack of a suitable culture media. Because of the low 
temperature at which the ice-cream is hardened and held, 
some investigators believe that there is a gradual change of 
the types of organisms or the survival of the fittest. 
This brings up the question as to the temperature at which 
the cultures should be incubated. Until a suitable media 
is prepared and a uniform temperature of incubation used, 
the counts of the organisms in ice-cream made by different 
investigators will not be comparable. 



CHAPTER XIV 

TESTING 

The determination of the composition of dairy products 
is a very simple yet important part of the ice-cream 
business. The fat and the solids not fat are the constit- 
uents usually determined. The most accurate method 
by which to buy all raw materials is on the basis of their 
composition. The finished product should be tested to de- 
termine its composition, regardless of whether or not it is 
sold on this basis. The testing of the finished product is 
necessary to check up the amount of materials used. By 
this means an accurate cost account can be kept and 
any variation in the composition of the product quickly 
discovered. 

THE BABCOCK TEST * 

The amount of fat in milk, cream and skim-milk can 
be ascertained quickly and accurately by means of the 
Babcock test. The essential requirements are that the 
operator be careful not to break the glassware and that 
the measurements are accurately made. 

142. Testing whole milk for fat. — The sampling is the 
most important operation of the test. "The sample to 

* Troy, H. C, " The Babcock test and testing problems," Cornell 
Reading Course Lesson 118, 1916; Ross, H. E., and Mclnerney, 
T. J., " The Babcock test with special reference to testing cream," 
N. Y. Cornell Exp. Sta., Bui. 337, 1913; Hunziker, O. F., " Testing 
milk and cream for butter fat," Ind. Exp. Sta., Circ. 42, 1914. 

183 



184 THE BOOK OF ICE-CREAM 

be tested should be thoroughly mixed before it is measured 
out. Mixing is done by shaking the vessel in which the 
milk is contained, or better still, by pouring the milk 
from one vessel into another. The fat in milk is lighter 
than the other constituents and soon rises to the surface. 
Unless great care is exercised an unfair sample will be 
taken. If the sample is an old one, such as a composite 
sample, it should be heated to a temperature of not over 
85° F. in order to soften the fat. The sample should not 
be heated above 85° F., since the fat is likely to separate 
in the form of an oil and when so separated it is impossible 
to remix it evenly throughout the sample.'^ 

143. Composite samples of milk. — The purpose of 
taking composite samples is to reduce the labor and ex- 
pense of testing. The true composite sample consists of 
aliquot portions of milk of several deliveries from the 
same patron. Composite sample jars must have a tight 
seal in order to prevent evaporation of moisture. Pint 
jars sealed with glass stoppers, cork stoppers, metal caps 
or screw tops may be used for this purpose. Bottles 
with paper caps and jelly glasses with tin lids do not 
furnish tight seals; they should not be employed. 

A separate jar is used for each patron and each jar 
must bear the respective patron's number. The jars 
should be thoroughly clean and, in order to guard against 
errors, they should be arranged on convenient shelves 
near the weigh-can in numerical order, grouping the jars 
of patrons of the same route together. Correct composite 
samples may be obtained by the use of a milk thief or a 
graduated pipette. If the milk thief is used, it is inserted 
into the weigh-can of milk of the entire delivery of one 
patron. The milk in the tube rises to the level of that 
in the weigh-can. The milk thief is then emptied into 



TESTING 185 

the sample jar. In case the graduated pipette is 
employed, a certain quantity of milk is taken 
for every pound delivered by the patron (usually 
about .1 cubic centimeter for every pound of 
milk delivered). The milk thief is the handier 
instrument of the two, but when the amount of 
milk delivered by different patrons varies con- 
siderably, the samples of milk from the larger 
producers are often too ample to be practical. 
Other so-called composite samples are taken 
by using the same measure for all milk receipts. 
In this case a small dipper holding about one 
ounce is commonly employed. With this dipper 
a sample of milk is taken daily from the weigh- 
can of each patron's milk and transferred into 
the sample jar. This method of composite 
sampling is not mathematically correct and the 
results tend to be less reliable, although experi- 
mental data show that the results average 
practically the same as when ahquot portions 
are taken. Evaporation causes the percentage 
of fat and other solids to increase, yielding mis- 
leading tests. It also tends to dry the milk on 
the surface, causing the formation of a tough, 
leathery layer. In this condition it is difficult 
to secure a representative portion for the test. 
This can be prevented: by giving the sample jar 
a gentle rotary motion after each addition of 
milk; by replacing the stopper properly after 
each addition of the milk; and by protecting 
the sample from excessive heat. Fermentation -^If -.^^'T 
may be prevented by the addition of a small ^^^k pi- 
amount of preservative, such as corrosive subli- pette. 



186 



THE BOOK OF ICE-CREAM 



mate, potassium bichromate or formaldehyde. It is 
usually best to have the temperature of the milk from 60° 
to 70° F. when measured into the test bottle; however, 
variation within reasonable limits will not affect the test 
since the coefficient of expansion of the milk 
is not high enough appreciably to affect 
the amount measured by the pipette. 

144. Measuring the sample. — The instru- 
ment for measuring the milk for the test is 
called a pipette. (Fig. 62.) It has only one 
graduation, 17.6 cubic centimeters, equiva- 
lent to 18 grams. The sample is measured by 
drawing the milk above the graduation and 
then placing the index finger over the end of 
the pipette. By carefully releasing the fin- 
ger, the column of milk can be lowered 
^^_ ^_ until the bottom of the meniscus is on a 
B 1 ia level with the 17.6 c. c. mark on the pipette. 

l;;|. i^3^ >fl It is absolutely necessary that the mark on 
l;-l^^ft^M the pipette be held on a level with the eye, 
i^^j^^ so as to show when the column of milk is 
Ifli^HU on a level with the mark. The milk is then 
^ge==:y transferred from the pipette to the test- 
FiG. 63. — Bab- bottle. (Fig. 63.) The pipette and the test- 
cock whole bottle should be slanted so that the milk 
will run down the bottle neck and not be 
forced out by the air coming from the 
bottle. Whole-milk test-bottles are of two kinds, those 
reading as high as 10 per cent and graduated in fifths, 
and those reading as high as 8 per cent and graduated 
in tenths. In each case the graduations give readings 
directly in terms of percentage, since the graduated 
part of the neck is made to hold a column of fat 




milk test- 
bottle. 



TESTING 



187 



which is a definite percentage of the weight of the milk 
taken. 

145. Adding the acid. — Sulfuric acid is added to the 
milk in the test-bottle, by means of a special measure 
which has only one graduation, 17.5 cubic centimeters. 
(Fig. 64.) The purpose of adding the acid is to destroy 
all the milk solids except the fat, which it does by moist 
combustion. In this process great heat is produced. 
This is advantageous, since 
the fat must be kept in a 
liquid condition in order to 
perform the test properly. 
The neck of the test-bottle 
gives percentage readings only 
when the fat is in a liquid 
condition. In adding the sul- 
furic acid, the bottle should 
be slanted, the same as in 
adding milk. As the acid is 
poured in, the bottle should 
be revolved so that the acid 
will wash down any milk 
that adheres to the neck, 
milk dries on 




Fig. 64. — Acid measures for 
Babcock test. 



If this is not done, the 
the neck and is lost in the test; it 
also causes a cloudy bottle-neck and obscures the fat 
column when the test is completed. The acid and milk 
should be mixed thoroughly as soon as the acid is added 
to the bottle, else portions of the sample might be 
charred and so lock up small particles of fat. It is well 
to mix the contents of the bottle for at least half a minute 
after all the milk has apparently been dissolved by the 
acid. The mixing is done by holding the bottle by the 
neck between the thumb and the index finger, and giving 



188 



THE BOOK OF ICE-CREAM 



/ 



\ 



it a rotary motion from the wrist (Fig. 65) ; if an up-and- 
down motion is used, the contents of the bottle are likely 
to be spilled. 

The strength of the acid is reckoned in terms of its 
density, which should be 1.82 to 1.83. A special instru- 
ment is used for testing the density, and, since this in- 
strument is seldom available in a dairy or a creamery, 
one of the best ways of testing the acid is actually to 
^^ perform a test with it and 

\ note the results. The acid 

\^\ should be of such strength 

V\ that it will turn the con- 

'\^-.„^ tents of the bottle to a 

dark brown as soon as 
mixed, and the mixture 
should turn an intense 
black after standing for 
about one minute. The 
best acid is colorless, yet 
it may be fairly dark and 
yet be fit for use. The 
acid should never contain any undissolved material, since 
this is likely to rise with the fat and obscure the reading. 
146. Whirling the sample. — ^After the acid and milk are 
thoroughly mixed, the samples are ready for whirling. 
The centrifuges used are of three main types (Fig. 66), 
those driven by hand power, by steam, and by electricity. 
The steam machines usually are considered best, since 
with them it is easy to maintain the proper temperature 
during the process of whirling. The hand and electric 
machines should perform equally as good work, provided a 
high enough temperature is maintained to keep the fat in a 
liquid condition. The frame of the hand machine should 



Fig. 65. — Diagram showing the 
motion and position of a 
test-bottle while mixing the 
milk and the acid. 



TESTING 



189 



always be filled with hot water before the bottles are 
whirled. In case of the four-bottle machines, which have 
no frames, the bottle cups, which are made large for that 
purpose, should be filled with hot water. Great care should 
be taken to have the machines balanced; by this is meant 
that for every bottle on one side of the machine there 
should be a bottle on the opposite side. The machines 
should also be well oiled, especially those driven by steam, 
which, because of the heat, soon dry out. 




Fig. 66. — Hand and power Babcock centrifuges. 



The sample is whirled for five minutes and then filled 
with hot water to the base of the neck, then whirled for 
two minutes and hot water again added so as to bring the 
fat within the graduated part of the neck. The sample is 
then whirled for one minute in order to bring all the fat 
into the graduated neck. Some operators of the Babcock 
test make two separate runs instead of three, filling the 
bottles to within the graduated neck after the first run. 
While this may give fairly good results, it is better to make 
three separate runs as indicated above and fill to the base 
of the neck the first time. This washes the fat free from 



190 THE BOOK OF ICE-CREAM 

any sediment and gives a clearer reading than would other- 
wise be obtained. 

147. Reading the test. — The sample should be read at 
once, before the fat column has had time to cool. In 
reading, the bottle should be held between the thumb and 
the index finger and the fat column should be on a level 
with the eye. The fat column in a whole-milk bottle is 
not large enough to be greatly affected by temperature 
unless it is extremely hot or cold. With a steam cen- 
trifuge, the temperature may be extremely high and thus 
the reading may be slightly increased. This danger may 
be avoided by allowing the bottles to stand for a minute 
at room temperature before reading. There is greater 
danger of reading the fat column at too low than at too 
high a temperature. It does not take long for the fat 
column to harden, and if the room is at all cold it is safer 
to set the test-bottles in water at about 140° F., having the 
water come above the fat column in the bottle. The ex- 
treme points of the column should be included in the read- 
ing (Fig. 67) since this method makes up very closely for 
minute particles of fat which are not brought to the sur- 
face during the process of testing. 

There are two methods of reading the percentage of 
fat in the neck of the bottle. The first is to obtain the 
difference between the bottom and the top of the fat 
column; if, for example, the bottom of the fat column 
rests on the 1.7 per cent mark and the top on the 5.8 per 
cent mark, the percentage of fat is 4.1 (5.8 — 1.7 = 4.1). 
The second method of reading is to count the whole per- 
centage and the tenth percentage marks covered by the 
fat column. Some operators make use of dividers in 
reading the fat column. The exact space covered is 
obtained, and one point of the dividers is placed on the 



TESTING 



191 




5.8<jJ 



zero mark and the other point against the graduated mark. 
The latter point will indicate the percentage of fat. There 
is no objection to this method, provided the fat column is 
never measured when it is above or below the graduations 
on the neck of the bottle. This is often done, yet there is 
no certainty that the space above or be- 
low the graduations is of the same size 
as it is within the graduations; in fact, 
it is usually larger. It is, therefore, easy 
to see the inaccurate results that may 
be obtained by taking a reading when 
the fat column is without the graduated 
part of the bottle neck. 

148. Appearance of a completed test. 
• — In a completed test the fat should be 
straw-yellow in color; the ends of the fat 
column should be clearly and • sharply 
defined; the fat should be free from 
specks and sediment; the water in the 
neck just below the fat should be clear; 
and the fat should be in the graduated 
part of the neck. Some of the defects 
and remedies are explained in the follow- 
ing paragraphs. 

If the fat column is too dark in color, Fig. 67. — Proper 

the acid may have been too strong, or too ^^^ *^ ^^^^ ^^^ 

1 11 1 .1 . percentage of fat 

much may have been used, or the tem- ^^ ^ Babcock 

perature of the milk and the acid may 

have been too high just before mixing. 

Mixing too slowly might also permit charring of part of 

the fat. The charred or darkened condition of the fat may 

be corrected to some extent by using less acid, by cooling 

both milk and acid below 60° F. just before mixing, and 



«.7V 



V^ 



whole milk test- 
bottle. 



192 THE BOOK OF ICE-CREAM 

by rapid, vigorous mixing continued for about a minute 
after all casein has been dissolved. 

If the fat column is too light in color, the acid was either 
too weak or too cold. This condition may be corrected to 
some extent in succeeding tests by using more acid and 
by having the milk and the acid at a slightly higher 
temperature when brought together. 

If the acid is not of the correct strength (specific gravity 
1.82 to 1.83), it will be difficult to obtain a correct test, 
but the trouble may be overcome partially by using more 
acid when it is weak and less when it is too strong. 

149. Care of the test-bottles. — As soon as all the bottles 
are read, they should be emptied. If allowed to stand 
until cold, they are more difficult to clean. The cleaning 
will be accomplished much more easily if the bottles are 
shaken violently up and down as the contents run out. 
A viscous sediment is formed by the action of the sul- 
furic acid on the milk, and the hot acid helps to loosen 
this if the bottles are well shaken. All Babcock glassware 
should be kept clean and bright. This can be done best by 
washing in hot water and washing-powder, and then 
rinsing in hot water. If many bottles are employed, a 
block and a top-board are very useful. The block has 
holes bored in it, of a size just large enough to hold the 
bottles, and it may be made to contain any desired num- 
ber. The holes in the top-board are large enough to admit 
the passage of the necks through them and the board 
rests on the shoulders of the test-bottles. In using this 
block and board, a number of bottles can be emptied at 
once and the hot bottles will not burn the hands of the 
operator^ 

150. Testing cream. — In testing cream there are three 
main factors to be considered: first, taking the sample; 



TESTING 



193 



second, getting the correct quantity of cream into the test- 
bottle; and third, correct reading of the completed test. 

151. Cream testing apparatus. — There are several 
forms and sizes of cream test- 
bottles. (Fig. 68.) The six-inch 
nine-gram bottles are preferable, 
especially for use in hand testers. 
This form has a scale graduated 
to read from to 50 per cent, the 
smallest scale divisions equaling 
.5 of 1 per cent. 

The balance for weighing cream 
test samples should be sensitive 
to .1 of a gram. There are 
several different types on the 
market. 

An ordinary four-quart pail 
would serve as a vat in which 
to bring the fat in the cream 
test-bottle to the proper tem- 
perature before adding the men- 
iscus remover and reading the 
test. The vat should be of such 
depth that when it is nearly full 
of water and the cream test- 
bottles are placed upright in it, 
the upper surface of the water 
and of the fat columns will be 
on about the same level. 

The thermometer should be of a 
form that registers each tempera- 
ture degree between the freezing and boiling points of water. 
That would permit of its use for a variety of purposes. 




Fig. 



68.— Babcock 
test-bottles. 



cream 



194 THE BOOK OF ICE-CREAM 

152. Sampling cream. — Cream differs from milk in 
containing a higher percentage of fat. Cream testing 
30 per cent of fat would contain 70 per cent of skimmed- 
milk substance, or milk-serum. Before sampling, the fat 
should be distributed evenly by thorough mixing or 
pouring. If the cream is old or lumpy or some has dried 
on the container, it should be warmed to about 95° F. 
and the lumps passed through a strainer before mixing. 
Then about two ounces should be placed in the sample 
bottle. 

153. Making the cream test. — The test sample must 
be weighed instead of measured because: 

1. The percentage of fat and the specific gravity of 
cream vary widely, and the weight of a definite volume 
would vary accordingly. 

2. Cream may contain bubbles of air or of carbon 
dioxide. 

3. Cream varies so widely in viscosity (sticky quality) 
that the amount delivered or the amount remaining in 
the pipette would be unknown. 

In testing cream 9 grams are used. The bottle should 
be balanced on the scales, and a 9-gram weight placed on 
the opposite side. The sample is mixed thoroughly, and 
by means of a pipette the cream transferred to the test- 
bottle until the scales exactly balance. About 9 cubic 
centimeters of water are next added to the test-bottle. 
(This water may be measured with suflftcient accuracy 
in the acid measure by filling it a little over halfway to 
the mark.) About 15 cubic centimeters of the acid should 
be placed in the test-bottle, and the contents mixed 
thoroughly. The cream and acid mixture should not 
turn black, but should remain coffee color. About 15 
cubic centimeters of acid give the proper concentration 



TESTING 



195 



remot^er' 



to dissolve the solids not fat, since the fat forms such a 
large part of the mixture and does not go into solu- 
tion. The bottles should be centrifuged and the water 
added exactly as in testing whole milk. 

154. Tempering the fat and 
reading the percentage. — When 
the last whirling is completed, 
the test-bottles should be trans- 
ferred to the tempering vat 
containing water held at a tem- rien/scus^ 
perature of 140° F. The water 
should be tempered in advance, 
and should be deep enough to 
surround the necks of the bottles 
to the top of the fat columns. 
After four minutes the bottles 
should be taken from the water, 
and the meniscus remover added 
at once by placing the .tip of a 
dropping pipette containing 
some of the substance against 
the inside of the bottle's neck, 
which is held in a slightly 
slanting position. The red 
liquid is allowed to run slowly 
down the inside of the neck 
and spread over the fat to a Fig. 69.— Method of read- 
depth of about one-fourth of ing the percentage of fat 
, Till! i_ • in a Babcock cream test- 
an mch. It should not mix , , 

with the fat. 

The meniscus remover is made from a purified mineral 
oil that has been colored red with alkanet root. It is 
sometimes called glymol. When placed on the top of a 




196 



THE BOOK OF ICE-CREAM 




fat column in a cream test-bottle, it flattens the curved 
surface, which is known as the meniscus. The test should 
be read immediately by subtracting the number on the 
scale at the bottom of the fat column from the number 
at the line of division between the fat and 
the meniscus remover. (Fig. 69.) Thus, 
if the bottom line of the fat column reads 
12 and the line between the meniscus re- 
mover and the fat at the top, 39, the 
percentage of fat would be 27. 

155. Testing skim-milk. — ^A special 
bottle is used for testing skimmed-milk. 
(Fig. 70.) The graduated neck of the 
test-bottle has a very small bore in order 
to measure the fat accurately. A second 
neck with larger bore is attached to pro- 
vide a convenient means of filling the 
bottle. The smallest divisions on the 
scale usually indicate .01 of 1 per cent, 
but on some bottles .05 of 1 per cent. 

The same care is necessary in mixing 
and sampling skimmed-milk and butter- 
milk that is required for whole milk, and 
the same pipette is used in measuring out 
the sample. The skimmed-milk is added 
to the test-bottle through the larger neck. 
Since a little more acid is necessary thor- 
oughly to free the fat in skimmed-milk, the measure 
should be filled to about a quarter of an inch above the 
mark. About one-half of the acid should first be added, 
and the mixture shaken thoroughly; then add the re- 
mainder, and again shake it vigorously for about a minute. 
One should avoid throwing undissolved casein into the 




Fig. 70.— Bab- 
cock skim- 
milk test- 
bottle. 



TESTING 197 

small neck while mixing the milk with the acid. The 
bottles are then centrifuged and filled in the same man- 
ner as in testing whole milk, except that the first whirl- 
ing should be continued for ten minutes instead of five, 
in order to bring up all the smaller fat globules. The 
percentage of fat is read immediately on completing the 
final whirhng. 

156. Modifications of the Babcock test for ice-cream. — 
The Babcock test as already explained cannot be used to 
test ice-cream, because it contains a large percentage of 
sugar. This sugar would char or burn and so interfere 
with the reading of the test. The following * are three 
modifications of the Babcock test. 

157. The glacial acetic and hydrochloric acid test. — 
"A representative sample of the ice-cream is taken and 
melted and thoroughly mixed; a 9 gram sample is weighed 
into an 18 gram Babcock cream test bottle. A mixture 
is prepared using equal parts of glacial acetic acid and 
concentrated hydrochloric acid. Twenty cubic centi- 
meters of this acid mixture is added to the 9 gram sample 
of ice-cream in the test bottle and is then well shaken. 
The bottle is placed in a water bath of 120° F. to 130° F., 
and shaken at intervals until a brown color appears. 
It is then placed in the Babcock centrifuge and the test 
completed in the same way as for testing cream and the 
reading multiplied by two." 

158. The sulfuric acid test.— ''To make the test with 
sulfuric acid, a 9 gram sample is weighed into an 18 gram 
test bottle. About 9 cubic centimeters of lukewarm 
water is then added to dilute the sample, in order to have 
about 18 cubic centimeters of mixture in the bottle. The 

*Sproule, W. H., "Cheese and butter-making," Ont. Agr. Coll., 
Guelph, Canada, Bui. "266, 1918. 



198 THE BOOK OF ICE-CREAM 

sulfuric acid is then added slowly, a little at a time, at 
minute intervals, shaking well after each addition until 
a chocolate brown color appears in the bottle. No defi- 
nite amount of acid can be stated as the quantity will 
vary with different ice-creams. As soon as the chocolate 
brown color appears in the ice-cream a little cold water 
may be added to check the action of the acid. The bottle 
is then placed in the centrifuge and the test completed 
in the usual way. The reading is multiplied by two." 

159. Acetic and sulfuric acid test. — ''Weigh a 9 gram 
sample of ice-cream that has been thoroughly mixed. 
About 9 cubic centimeters of water are then added to 
dilute the sample. Add 5 cubic centimeters of acetic 
acid and then add carefully 6 to 8 cubic centimeters of 
sulfuric acid. Centrifuge, and then add water the same 
as in other tests. If using an 18 gram bottle, multiply 
the reading by two, to obtain the per cent fat in the ice 
cream. A 9 gram bottle which is graduated to give the 
percentage of fat directly needs no correction when read- 
ing." 

160. The lactometer. — Because not only the fat but 
all the solids are utilized in the ice-cream, it is important 
to know the amount of total solids and the solids not fat 
in the milk. This is ascertained by determining the 
specific gravity of the milk and knowing the fat-content; 
the solids not fat can then be calculated. The specific 
gravity of liquids is measured by an instrument called a 
hydrometer. Its use is based on the fact that when a 
solid body floats in a liquid, it displaces a volume of 
liquid equal in weight to its own. Hydrometers are in 
many cases so made that the specific gravity can be read 
at the poinli where the scale is even with the upper surface 
of the liquid. A hydrometer especially adapted to milk 



TESTING 199 

is called a lactometer. There are two in coimnon use, 
the Quevenne and the Board of Health. 

The Quevenne lactometer is a long slender hollow piece 
of glass weighted at the bottom to make it float 
in the milk in an upright position. (Fig. 71.) 
The upper end is slender and contains the scale 
which is graduated from 15 at the top to 40 
at the bottom. Each reading on the scale cor- 
responds to the point marked specific gravity 
on a hydrometer, except that the figures are 
not complete. For example, 15 on the Que- 
venne scale means a specific gravity of 1.015; 
a reading of 30 means a specific gravity of 
1.030, and so on. The Quevenne lactometer 
is graduated to give correct readings at 60° F. 
The milk should be at this temperature; if 
above or below this, a correction must be made 
to the reading. The temperature should not 
be more than 10 degrees above or below 60° F. 
The correction for each degree in variation 
can be made by adding or subtracting 0. 1 from 
the lactometer reading, as the case may be. 
If the temperature is above 60° F., the correc- 
tion is added to the lactometer reading; if be- 
low 60° F., it is subtracted. The reading 
should be taken when the lactometer is float- 
ing free in the milk. The scale is read ex- 
actly at the surface of the milk. The better 
lactometers have a thermometer with the Fig. 71.— 

scale just above or opposite the lactometer Quevenne 
1 lactometer, 

scale. 

The Board of Health lactometer is very similar to the 

Quevenne except that the scale is graduated from to 



200 



THE BOOK OF ICE-CREAM 



120. (Fig. 72.) The point on the scale that floats at the 
surface in water is represented by 0, and 100 represents 
the specific gravity of 1.029. On the Board 
of Health lactometer the 100 degrees or divi- 
sions from to 100 equal 29 divisions on the 
Quevenne. Therefore, one division on the 
Board of Health equals 0.29 of a division on 
the Quevenne. To convert Board of Health 
reading to Quevenne, multiply by 0.29 and to 
convert Quevenne to Board of Health, divide 
by 0.29. The correction for temperature above 
or below 60 F. is made the same as with the 
Quevenne, except 0.3 is added or subtracted 
from the lactometer reading instead of 0.1 as 
with the Quevenne. 

161. Calculating the solids not fat in the 
milk. — When the lactometer reading and the 
fat-content of the milk are known, there are 
several formulas for calculating the solids not 
fat. In the following, L equals Quevenne 
lactometer reading at 60° F.; F. the percent- 
age of fat in the milk, and S. N. Fo the solids 
not fat in the milk. 



I ii 



Fig. 72. — 
Board of 

Health 
lactometer. 



^i±^ = S.N.F. 

o . o 



L + F 



= S. N. F. 



4 + 0.2F + 0.14 = S. N. F. 



162. Testing milk for acidity. — Several tests on the 
market are used to determine the amount of acid in milk. 



TESTING 



201 



Each is based on the principle of chemistry, that acids 
and alkahes tend to neutralize each other. The acidity 
of milk is of two kinds, apparent and real. The apparent 
acidity is due to the acid reaction of the acid phosphates 
and casein. It usually varies from .08 to .1 per cent. 
The real acidity is due to 
the action of the bacteria 
on the milk-sugar. It is 
usually assumed when de- 
termining the acidity of 
milk, that all the acidity is 
due to the presence of the 
lactic acid. 

The process by which 
the acidity is determined 
is called titration. A 
known quantity of milk is 
placed in a cup or flask 
and an alkali of known 
strength measured into it 
by means of a burette. 
(Fig. 73.) The unit of 
measure is the cubic centi- 
meter. The burette is 
usually graduated into 
tenths of a cubic centimeter. The point at which all the 
acid in the milk is neutralized by the alkali is told by 
means of an indicator. The one commonly used is 
phenolphthalein. This is colorless in the presence of 
acid and pink in the presence of alkali. If two or 
three drops of indicator are put in the milk, the color 
will not change because it is ^cid. When just enough 
alkali has been added to neutralize the acid, the color 




Fig. 73. — Nafis acid test. 



202 THE BOOK OF ICE-CREAM 

will change to pink. The alkali should be added slowly 
and gradually the acid will be neutralized by the alkali 
until at last a uniform pink color appears, which will 
slowly fade away. All the acid has been neutrahzed and 
the amount of alkali used should be read from the burette, 
when the first change to a uniform pink color is noted. 

The different acid tests on the market are sold under 
various trade names, such as Nafis, Manns, Marschalls 
and Farringtons. Each is based on the same principle 
but uses different amounts of milk and alkali solutions 
of various strengths. However, in each test the amount 
of milk and strength of the alkali solution are such that 
the number of cubic centimeters of alkali used are read 
directly as the percentage of acid in the milk. This 
eliminates all calculations. If the strength and amount 
of the alkali solution required to neutralize the acid in the 
milk is known, and the amount of milk used, accurately 
measured, the percentage of acid can be calculated. 

It is a chemical fact that one cubic centimeter of a normal 
solution of alkali will neutralize exactly .09 grams of lactic 
acid. In actual practice an alkali solution weaker than a 
normal solution is employed. This is because the latter is 
so strong that only a small amount would be used, hence a 
small variation in the amount would make a big variation 
in the final percentage. A l/lO or 1/20 normal solu- 
tion (expressed n/lO or n/20) is commonly used. One 
cubic centimeter of a n/10 alkali solution would neutral- 
ize .009 grams of lactic acid. An example will illustrate 
how to figure the results. Suppose it took 4 c. c. of n/lO 
alkah solution to neutralize the acid in 18 grams of milk. 
What is the percentage of acidity in the milk? One cubic 
centimeter of n/lO alkali will neutralize .009 grams of 
lactic acid. Four cubic centimeters will neutraUze 4 X 



TESTING 203 

.009 = .036 grams of acid; .036 grams of acid divided 
by 18, the grams of milk used, multiply by 100, equals 
.20 per cent acidity in the milk. This may be expressed 
thus: 

.009 X No. c. c. alkali used ^ ^^ ^ ^^ ^^^^ ^j ^^-^^^ 

number of grams material used 

Then the above problem would be expressed thus: 

•^^^ ^ ^ X 100 = .20 per cent acidity 
18 

163. Test for formaldehyde. — Sometimes formalde- 
hyde is added to the milk to preserve it. It can be de- 
tected easily when making the Babcock test. The re- 
quired amount of milk is measured with the pipette into 
the test-bottle and a few drops of ferric chloride added. 
The required amount of sulfuric acid is next put in. If 
formaldehyde is present, a lavender-colored ring will 
appear between the layer of acid and the layer of milk. 
If the contents of the bottle are slowly mixed, the dis- 
solving casein will take on a lavender color. The test 
will not work if the milk is too old or too much of the 
formaldehyde has been added. Because of the presence 
of ferric salts in the sulfuric acid as impurities, it is not 
always necessary to add the ferric chloride although it 
is best to do so. 

164. Test for boiled milk. — It is often desirable to 
know whether or not milk has been boiled. The following 
test will give this result: Two sets of reagents may be 
used: (1) hydrogen peroxide, potassium iodide and starch, 
(2) hydrogen peroxide and paraphenylenediamine hydro- 
chloride. In milk there is an enzyme glactase which may 
be destroyed by heat. When the milk has not been 



204 THE BOOK OF ICE-CREAM 

heated, this enzyme sets free the oxygen from the oxidiz- 
ing agent. In case of the first materials, the glactase 
sphts up the hydrogen peroxide. The free oxygen splits 
up the potassium iodide and liberates free iodine. The 
starch in the presence of free iodine turns blue. In the 
second case, the free oxygen acts on the paraphenyl- 
enediamine hydrochloride and turns the solution blue. 
In either case if a blue color results, the milk has not 
been boiled. Hydrogen peroxide often contains sulfuric 
acid. When this is the case, the reagent is useless for the 
test with starch as the free acid would break up the 
potassium iodide. If this condition exists a blue color 
would result, whether or not the milk had been pasteur- 
ized. 

TESTING BUTTER FOR FAT, MOISTURE, AND SALT 

When large quantities of butter are used in the making 
of ice-cream, it is important that it be tested. Sweet or 
unsalted butter is best adapted for the making of ice- 
cream. If a sample is suspected or tastes salty, a test 
should be made to determine the exact percentage. In 
order to make cream of a desired percentage of fat, the 
composition of the butter must be known. 

165. Preparing the sample. — Experiments * indicate 
that the salt and moisture in the butter are not uni- 
formly distributed. This shows the need of careful 
sampling and preparation of the sample before testing. 
The sample should be placed in a wide-mouth ground- 
glass stoppered glass jar. The bottle should be kept 

*Lee, C. C, Hepburn, N. W., and Barnhart, F. M., "Studies of 
factors influencing the composition of butter," 111. Exp. Sta., Bui. 
137, 1909; Guthrie, E. S., and Ross, H. E., "Distribution of moisture 
and salt in butter," N. Y. Cornell Exp. Sta., Bui. 336, 1913. 



TESTING • 205 

stoppered to prevent evaporation. A hardwood stick is 
best for stirring. The bottle containing the sample to 
be tested should be warmed to a temperature of 110°- 
120° F. until the butter is the consistency of thick cream. 
This may be done by placing the bottle in warm water. 
While it is being warmed, it should be stirred to obtain 
a uniform mixture. It should not be heated too much 
or the water and fat will separate and it is almost impossi- 
ble to mix them again. When the butter is about the 
consistency of thick cream, it should be cooled and stirred 
thoroughly while cooling. This insures a uniform com- 
position in the butter. The cooling should continue 
until the butter is quite firm. 

166. Testing butter for fat. — After the sample has 
been prepared to test as outlined above, 3-5 grams of 
this butter should be weighed into a cream test-bottle. 
The addition of warm water, warm enough so that the 
fat will melt, will bring the weight of the butter and water 
to approximately 18 grams. Sufficient acid to give a 
light brown color should be added. It will take less acid 
than for cream because there are fewer solids not fat. 
The procedure is the same as in testing cream for fat. 
After the test has been read, the percentage of fat in the 
butter must be calculated. 

167. Testing butter for moisture. — Several moisture 
tests * are on the market. The following is a very simple 
one: 

The apparatus used is an alcohol lamp, iron stand, 
asbestos sheet, hot pan lifter, aluminum cup for holding 
the sample, and a very sensitive scale. To make the test, 
10 or 20 grams of the prepared sample of butter as de- 

*Ross, H. E., ''Butter moisture tests," N. Y. Cornell Exp. Sta., 
Bui. 281, 1910. 



206 THE BOOK OF ICE-CREAM 

scribed in paragraph 165, should be weighed into the 
aluminum cup. The cup should be dry and about the 
same temperature as the room. The alcohol lamp is then 
placed under the iron stand and the asbestos sheet on the 
stand. The lamp is lighted and the cup put on the as- 
bestos sheet. It is well to light the lamp at least two or 
three minutes before placing the cup on the asbestos in 
order to heat it and save time. The heat of the flame 
may be increased or diminished by raising or lowering 
the wick. The cup should always be handled with the 
hot pan lifter, as by so doing it will be kept clean and 
errors in weight due to dirt on the cup will be avoided. 

While the sample is heating, it should be shaken from 
time to time as this breaks up the blanket of casein on the 
surface and hastens the escape of moisture. As soon as 
the casein has lost its snow-white color, the cup should 
be removed from the flame. When the moisture has all 
been driven from the sample, a slightly pungent odor may 
be noticed. This may also be used as a guide to tell when 
the sample has been heated enough. The foam begins to 
subside at this point. Often one or two small pieces of 
casein are slow to give up their moisture. This is indicated 
by the snow-white color of the pieces. Evaporation can 
be hastened by shaking the sample with a rotary motion 
and thoroughly mixing these pieces with the hot liquid. 
If this is not done, one might have to heat the sample 
so long that some of the fat, which had already given up 
its moisture, would volatilize. 

After all the moisture is driven off, the sample is allowed 
to cool to room temperature. While cooling, the cup 
should be covered with something (a sheet of paper will 
do) to prevent the sample taking up moisture from the 
atmosphere. After cooling, the cup is placed on the 



TESTING 207 

scales. The sample is lighter than before heating, because 
it has lost its moisture. The loss in weight divided by 
the weight of butter taken gives the percentage of mois- 
ture in the sample of butter. 

168. Testing butter for salt. — The following test has 
been devised by H. C. Troy of Cornell. The materials 
used are: One ten cubic centimeter burette graduated to 
tenths of a cubic centimeter; Babcock milk pipette; one 
white cup; one pint bottle marked to show the line at 
the upper surface of the liquid when the bottle contains 
300 cubic centimeters; standard tenth normal silver ni- 
trate solution (dissolve 17.5 grams of so-called chemically 
pure silver nitrate in water and make the volume up to 
1000 cubic centimeters) ; 10 per cent solution of potassium 
chromate for indicator. 

To make the test, three or four ounces of the butter 
should be softened by warming to a pasty condition in 
a fruit jar or wide-necked bottle. It should be mixed thor- 
oughly with a table knife or strip of wood in order evenly 
to distribute the moisture. Ten grams of the mixed but- 
ter should be weighed into a dish and washed with hot 
water into the pint bottle. (If a moisture test was made 
on ten grams of the butter, the substance remaining in 
the cup may be used for the salt test.) Enough hot water 
should be added to bring the surface up to the 300 cubic 
centimeters mark on the bottle, the stopper placed in 
the bottle and shaken vigorously for about half a minute. 
The bottle should rest for about five minutes, and a Bab- 
cock milk pipette of the watery portion drawn (17.6 
cubic centimeters) and placed in a white cup. Three or 
four drops of the potassium chromate solution should be 
added, stirred, and run in the standard silver nitrate 
solution from the burette, with constant stirring until 



208 THE BOOK OF ICE-CREAM 

the color of the substance in the cup changes to a perma- 
nent brownish red. On the burette scale the amount of 
standard silver nitrate solution used may be read. 

Each one-tenth of a cubic centimeter of standard silver 
nitrate solution employed equals one-tenth of 1 per cent 
of salt in the butter. 

169. Test for viscosity. — It is often desirable to test 
milk, cream or the ice-cream mix for viscosity. There 
are several viscometers for the purpose. The simplest 
way to determine the viscosity is to heat and draw out 
the end of a pipette so that it has a very small opening. 
The pipette can then be filled with the material to be 
tested. The length of time required to empty the pipette 
determines the viscosity. The more viscous the material, 
the longer it takes to run out of the pipe. In order to 
make comparisons, the materials should be at the same 
temperature each time. This is a very important factor. 

170. Standardization.— One of the main requirements 
for a successful ice-cream business is uniformity of quality. 
In order to obtain this, it is necessary to have a product 
each time containing the same percentage of fat. As it 
is impossible always to secure cream of a uniform fat- 
content, the cream and milk used in the ice-cream must 
be standardized.* 

Standardizing milk or cream consists in raising or low- 
ering the fat-content to a fixed standard. This is done 
by adding to the material milk or cream of a higher or 
lower percentage of fat. In standardization two classes 
of problems are involved: first, one in which a certain 
fixed amount of milk is to be made up or a certain amount 
of standardized milk is desired; and second, in one in 

* Ross, H. E., Guthrie, E. S., and Fisk, W. W., "Practical examples 
in dairy arithmetic," Cornell Reading Course, Vol. 5, No. 98. 



TESTING 209 

which a certain amount of milk or cream is to be used and 
enough of another product added to make the mixture 
test a certain percentage of fat. In the latter case, the 
amount of the mixture is indefinite. 

The original method of computing problems in stand- 
ardization is long and difficult, but a comparatively simple 
scheme has been devised by R. A. Pearson. The method 
is as follows: 

Draw a rectangle and place in the center of it the per- 
centage of fat desired. Place at the left-hand corners of 
the rectangle the percentages of fat in the materials to 
be mixed. Subtract the number in the center from the 
larger number at the left of the rectangle. Place the re- 
mainder on the diagonally opposite right-hand corner of 
the rectangle. Subtract the smaller number on the left- 
hand corner from the number in the center and place the 
remainder on the diagonally opposite right-hand corner 
of the rectangle. 

The two numbers on the right-hand corners of the 
rectangle represent the number of pounds of material 
required. If these two numbers 
are added they will express the 
number of pounds of the mix- 
ture, which will contain a per- 
centage of fat expressed by the 
number in the center of the rectangle. In each case 
the number on the right-hand corner corresponds in fat 
test to the number on the left-hand corner directly 
opposite. * 

Problem: How many pounds of 40 per cent cream and 
3 per cent milk must be mixed to make milk testing 5 
per cent? Using the diagram as described, the result 
shown in diagram above is obtained. 





210 THE BOOK OF ICE-CREAM 

This means that if 2 pounds of 40 per cent cream are 
mixed with 35 pounds of 3 per cent milk, the result will 
be a 37 pound mixture testing 5 per cent. Answer. 

Problem: How many pounds of 28 per cent cream and 
3 per cent milk will be required to make 500 pounds of a 
mixture testing 4 per cent? In this problem a definite 
number of pounds of the mixture is required. 

According to the diagram, 1 
pound of 28 per cent cream is re- 
quired to every 24 pounds of 3 
per cent milk to make a mixture 
testing 4 per cent. This would 
make 25 pounds of the mixture, but 500 pounds is the 
amount desired. In other words, the number of pounds 
desired is 20 times larger than the number of pounds on 
hand (500 ~ 25 = 20). The amounts must be kept in 
the proportion of 1 : 24. Therefore, in order to get a 500 
pound mixture it is necessary to multiply both the 1 and 
the 24 by 20. This would give a result of 20 pounds of 
28 per cent cream and 480 pounds of 3 per cent milk, 
which mixed will equal 500 pounds of 4 per cent milk. 
Answer. 

This problem may also be worked by simple proportion : 

l:25::x:500 

25 X = 1 X 500 

25 X = 500 

X = 20, number of pounds of 28 per cent cream there 
will be in the 500 pound mixture. . Answer. 

If there are 20 pounds of 28 per cent cream in the 500 
pound mixture, the remainder will necessarily be 3 per 
cent milk. 

Therefore, 500 — 20 = 480, number of pounds of 3 per 
cent milk. Answer. 



TESTING 211 

The number of pounds of 3 per cent milk can be found 
directly by simple proportion: 

24 :25 ::x : 500 

25 X = 24 X 500 = 12,000 

X = 480, number of pounds of 3 per cent milk. An- 
swer. 

Proof: In working problems in standardization it is 
always wisest to prove the answer, as this is the best 
method of checking the work for mistakes. 

According to the conditions of the problem there would 
be 500 pounds of 4 per cent milk. This amount of milk 
would contain 20 pounds of fat (500 X .04 = 20). Ac- 
cording to the results the 500 pounds would be made up 
of 480 pounds of 3 per cent milk and 20 pounds of 28 
per cent cream. The 480 pounds of 3 per cent milk would 
contain 14.4 pounds of fat (480 X .03 = 14.4). The 20 
pounds of 28 per cent cream would contain 5.6 pounds 
of fat (20 X .28 = 5.6). 14.4 + 5.6 = 20 

Since the 500 pounds contain 20 pounds of fat, and the 
materials of which the 500 pounds are made up furnish the 
20 pounds of fat, the problem is worked correctly. 

Problem: How many pounds of 3 per cent milk must 
be mixed with 150 pounds of 28 per cent cream to make 
a mixture testing 4 per cent? In 
this problem the number of 
pounds to be made up is not def- 
initely known. 

Working the problem by the ^ \ '^ 

rectangle method, 1 part of 28 per cent cream is required 
for 24 parts of 3 per cent milk. According to the terms 
of the problem, 150 pounds of 28 per cent cream must 
be used, and this is 150 times as large as in the above 
proportion. 




212 THE BOOK OF ICE-CREAM 

The 28 per cent cream and 3 per cent milk must be 
kept in the proportion of 1 : 24, and since the amount of 
28 per cent cream is to be increased 150 times, the 3 
per cent milk must also be increased 150 times. This 
would give 150 pounds of 28 per cent cream (1 X 150) 
and 3600 pounds of 3 per cent milk (150 X 24 = 3600), 
making in all 3750 pounds (150 + 3600 = 3750) of a 4 
per cent mixture. 

This problem may also be worked by simple propor- 
tion: 

24 :1 ::x : 150 

X = 3600, the number of pounds of 3 per cent milk 
required. 

Proof: The 3750 pounds of 4 per cent milk will contain 
150 pounds of fat (3750 X .04 = 150). 

If the 150 pounds of 28 per cent cream and 3600 pounds 
of 3 per cent milk furnish 150 pounds of fat, the problem 
is correct. 

3600 X .03 = 108, number of pounds of fat in milk. 

150 X .28 = 42, number of pounds of fat in cream. 

108 + 42 = 150, number of pounds of fat in mixture. 
Answer. 

The percentage of fat, or solids not fat, or total solids 
in a given batch may be computed if the percentage 
composition of the materials is known. Compute the 
total number of pounds of the desired material in each of 
the products used and divide by the total weight of the 
batch. For example, to find the percentage of fat in a 
batch, compute the pounds of fat in each material and 
find the total number of pounds of fat. Dividing the 
result by the total weight of the mix will give the per- 
centage of fat in the mix. The solids not fat or total 
solids may be computed in the same way. By reversing 



TESTING 



213 



these calculations, the percentage of fat necessary in the 
milk or cream to yield a mixture containing a certain 
percentage of fat can be computed. 

171. Benkendorf * test for over-run in ice-cream. — 

With this simple outfit (Fig. 74), it is possible at all times 




^ J l'^ 



YiG. 74.— Apparatus for testing ice-cream over-run by the Benken- 

dorf method. 

and without data as to the volume or weight of the ''mix," 
for the manager of the factory to determine the over-run 
in any lot of ice-cream made by his employees. 
Method of making the over-run test 

To obtain a 50 cubic centimeter sample, the metal 
sampler should be pressed down into the hardened ice- 

*Benkendorf, G. H., et al., "Some improved dairy tests and 
methods," Wis. Exp. Sta., Bui. 241, 1914. 



214 THE BOOK OF ICE-CREAM 

cream until it is entirely below the surface, and allowed 
to remain there for a minute or two, to become chilled. 
Then it should be drawn out and the protruding ice-cream 
removed from both ends of the sampler with a case knife 
or small piece of flat metal. (When a continuous freezer 
is used, a metal sampler with a closed bottom, like a cup, 
can be held under the spout of the freezer until heaping 
full, then the surplus scraped off.) 

The 200 cubic centimeter flask should be filled exactly 
to the mark on the neck with hot water and the sampler 
held in the funnel, the stem of which is inserted in the 
neck of the 250 cubic centimeter flask, a little of the hot 
water poured over the sampler until the ice-cream slips 
out of it, then all the remaining hot water slowly poured 
over this. 

The foam which appears in the neck of the 250 cubic 
centimeter flask should be destroyed by adding 1 cubic 
centimeter (or 2 cubic centimeters if necessary) of ether 
with the pipette. As soon as the foam has disappeared, 
the flask may be filled with water exactly to the 250 cubic 
centimeter mark by means of the burette, which has 
previously been filled to the zero mark. 
How to make the calculations. 

The number of cubic centimeters of water and ether 
used to bring the volume up to the 250 cubic centimeters 
mark, represents the shrinkage which the 50 cubic centi- 
meter sample of ice-cream has undergone when melted. 
Subtracting this shrinkage from 50 gives the original 
volume of the "mix" before freezing. To determine the 
percentage of over-run, the number of cubic centimeters 
of shrinkage should be divided by the number of cubic 
centimeters that were in the original mixture. 



TESTING 215 

Example: Cubic centimeters 

Sample used 50 

Ether used to reduce foam 1 

Water used to bring to 250 c. c. mark 15 . 5 

Water and ether used (15.5 + 1) 16.5 

Volumeof "mix" before freezing (50 — 16.5) 33.5 

Per cent of over-run (16.5 -^ 33.5) 49.25 per cent 

172. Test to determine the hardness of ice-cream. — 

The apparatus * used for determining hardness was 
reproduced from the description of a similar piece of 
apparatus by A. E. Perkins. It consisted of a wooden 
frame made of 2 X 4-inch lumber, with cross pieces on 
the bottom so that it stood firmly in an upright position. 
A cross piece, about one foot from the bottom of the 
frame, made the support for holding the sample. At the 
top of this support was an adjustable wooden screw for 
holding the electro-magnet. By adjustment with this 
screw, the magnet could be lowered or raised several 
inches. This adjustment was necessary so that the height 
of the needle could be made constant with all samples. 
The drop frame which holds the needle and which is held 
up by the magnet until the electric current from the 
batteries is broken, was made from very light Ys-inch 
piping, the width being sufficient to give a free drop 
without touching the mold, and long enough to reach 
below the platform when the magnet was at its highest 
point. The wires from the magnet led to a cut-off key 
on the side frame and from there to a pair of dry cells 
from which the current was derived. The needles were 
of different sizes but the same weight, thus eliminating 
the necessity of adjustments to obtain constant weight. 

* Holdaway, C. W., and Reynolds, R. R., "Effects of binders upon 
the melting and hardness of ice-cream," Va. Exp. Sta., Bui. 211, 
1916. 



216 THE BOOK OF ICE-CREAM 

The needles were marked from their points upward, in 
centimeters and fractions thereof, to show the depth of 
penetration. The height of the drop was always 100 
millimeters, being measured carefully with a metric rule 
before each determination. 

In making the determination, the frame with a suitable 
needle and weights is suspended from the electro-magnet, 
and the material to be tested placed in position beneath 
the needle, the height being regulated as already described. 
The frame is then released by means of the key. The 
depth of penetration is ascertained from the marks on 
the needle and confirmed by measuring with the metric 
rule. The suspension of the weights far below the needle 
brings the center of gravity of the falling portion of the 
apparatus below the point of the needle, causing the latter 
invariably to assume a vertical position, rendering it 
much easier to ascertain the true depth of penetration 
than would be the case if the point of the needle were at 
or below the center of gravity. After its release by the 
electro-magnet, the apparatus meets with no resistance 
in its fall, except that offered by the air, until the point 
of the needle reaches the surface of the cream. The 
amount of weight acting on the needle is known and the 
distance through which it falls is constant. If, however, 
too much weight or too small a needle is employed, the 
latter continues to sink slowly, making an accurate read- 
ing of the depth of penetration impossible. In the reverse 
case, with too large a needle or too little weight, the pene- 
tration is of course much less and the percentage of experi- 
mental error proportionately greater. As there was a 
large variation in the hardness of the various fillers, three 
sets of neledles were employed and in this way much of 
the error was eliminated. The size of the needles were: 



TESTING 



217 



large 5/16 inch or 7.93 millimeters, medium 4/16 or 6.35 
millimeters, and small 3/16 or 4.76 millimeters in diameter. 
The tests were made by allowing each needle to penetrate 
the ice-cream three times. The point of penetration was 
varied from center to points near the edge as there was a 




17 16 29 14 15 19 18 24 

Fig. 75. — Mojonnier tester for fat and total solids. 

possibility of the cream being harder near the edge than 
in the center. The depth of penetration of each needle 
was expressed in millimeters. The work was done in a 
cold storage with the temperature near 0° C. 



218 THE BOOK OF ICE-CREAM 



MOJONNIER TESTER 

Considerable time is required to make some of the tests, 
after the chemical method, such as those for solids in 
the different milk products. Mojonnier Brothers have 
devised a test both for fat and solids which is accurate 
and saves much time. A description of this test follows. 
The machine is shown in Fig. 75. The numbers on the 
arrows refer to numbers in the text, as follows: 

(1) All tests for butter-fat are made upon this side. 

(2) All tests for total solids are made upon this side. 

(3) Butter-fat extraction flasks in centrifuge baskets. 

(4) Eight 33^ inch aluminum dishes for butter-fat tests (the 
larger ones) . The one tall counterpoise counterbalances each dish. 
Fat dishes have no covers. 

(5) Eight 3-inch aluminum dishes for solids tests (the smaller 
ones). The one short counterpoise counterbalances each dish. 
Cover prevents absorption of moisture from the air during weigh- 
ing. Counterpoise balances both dish and cover. 

(6) Fat vacuum oven. The temperature in this oven is main- 
tained at 135 deg. C. Thermometer (10) extends into vacuum 
oven and rests on hot plate. The mercury bulb fits snugly in 
removable brass mercury well. Once a month this mercury well 
should be refilled with mercury. Be careful to see that the well 
always forms good contact with hot plate. Regulate temperature 
by rheostat (15). 

(7) Cooling chamber. Water at room temperature from the 
tank (28) in bottom part of the fat tester, is pumped by means 
of circulating pump in power unit (20) through the flat hollow 
sheet brass plate inside the cooling chambers and from there 
into pipe back of tester back into tank. Operator must watch 
outlet on cooling chamber and see that water is flowing at all 
times while the motor is turned on. If water is not running, you 
may know that the water in the storage tank is low. Keep tank 
filled at all times. In winter to prevent freezing, put a gallon 
of denatured alcohol into tank. 

(8) Solids oven. Maintained at 100 deg. C. Regulate tem- 
perature by means of rheostat (16). Follow instructions in (6) 
above closely for method of placing thermometer. Keep joints 
at door clean, and grease with vaseline sliding surfaces. This 
insures a more perfect vacuum. 



TESTING 219 

(9) A 250 deg. C. thermometer for solids oven. Wire on rubber 
connections. 

(10) A 250 deg. C. thermometer for fat oven. 

(11) Vacuum gauge is on main suction line from vacuum 
pump. This registers vacuum of either oven, or of both ovens 
simultaneously. 

(12) Sohds plate. Maintained at 180 deg. C. The ther- 
mometer can be placed in nickel plated mercury well with base 
that rests directly upon plate. See that this side is level. 

(13) Fat plate. Maintained at 135 deg. C. During the evap- 
oration of ether from the dishes, the temperature falls. Some 
operators prefer to keep temperature at 150 deg. C. to start and 
place dishes only halfway upon plate. As the plate cools, the 
dish may be pushed over until it is entirely upon hot plate. 

(14) Rheostat for fat plate. Turning rheostat handle forward 
increases temperature. Turning handle backward decreases 
temperature. It is important to see that the lever on handle 
makes good contact with separate buttons and not with two 
buttons at a time. As soon as right button has been found that 
maintains constant temperature, mark this point upon rheostat 
rim. In starting up tester, each day, you may turn handle on 
full and then when temperature is up to within 10 degrees of 
right point, turn handle back to previously marked button. 
Same instructions apply for all rheostats. 

(15) Rheostat for fat oven. 

(16) Rheostat for solids oven. 

(17) Rheostat for solids plate. 

(18) Handle for centrifuge. 

(19) In case the operator forgets temperature and time for 
treating samples at various points, he may notice the temperature 
and time below each snap switch for each hot plate. 

(20) The power unit consists of a high vacuum pump, a water 
circulating pump, and a suction fan all driven by a single motor. 
Vacuum pump must be submerged in oil furnished with tester. 
Fill chamber up to air cock with. oil. 

(21) Automatic burettes. The cans holding the water, am- 
monia, alcohol, ethyl ether and petroleum ether are placed in 
this order. This is the order in which these reagents are added 
to the flasks containing the weighed sample of milk. Each divi- 
sion delivers the proper amount for a single extraction. 

(22) Place this hood over fat dishes when evaporating off 
ether, so that the suction fan may draw off ether fumes to out- 
side of building. 

(23) Fasten these legs to floor with lag screws. 



220 THE BOOK OF ICE-CREAM 

(24) This side need not be fastened to floor. In case it is 
necessary to take out power unit, it is necessary only to dis- 
connect connections in rear of machine and move this part of 
machine forward. 

(25) The balance is the heart of the machine. Operator must 
keep it level, clean and handle it carefully. Raising and lowering- 
knife edges must be done gradually and with care. Make it a 
habit of cleaning balance daily. The weights must be kept clean, 
and as soon as you notice that some of the smaller weights are 
wearing out, order new ones. 

(26) This cock exhausts vacuum from oven when cock (27) is 
closed. It must be kept closed when vacuum is turned on oven. 

(27) This cock puts vacuum from main line into vacuum oven. 
Set of cocks at right is for solids oven, and at the left for fat 
oven. 

(28) In top of fat plate holder there is a hole communicating 
with suction fan on power unit. When the exhaust pipe on 
suction fan is run out of window of laboratory and the hood is 
over the dishes, all fumes of ether will be driven from the room. 

(29) Screw stool to floor. 

(30) A wash stand for washing all glassware should be pro- 
vided 

173. General preliminary information. — In the opera- 
tion of the Mojonnier tester, several steps remain the 
same regardless of the product being tested. Among these 
are the following: 

(1) How to use the balance. 

Two types of balances are in principal use — namely, the old 
type with graduated beam and rider, and the new type called 
''Chainomatic" with the chain and vernier. The care to give 
to either type of balance is the same. The difference is in the 
method of balancing the object to be weighed, and of reading 
the weight. These points will be discussed separately. 

A balance is a delicate instrument, and care needs to be exer- 
cised in its use at all times. The weights likewise require careful 
handling. Lack of care in the weighing operations may lead to 
entirely erroneous results, and thus defeat the object aimed at, 
namely, accuracy of the tests. 

The balance is inclosed in a glass case to shield it from dust, 
air currents, and moisture. Perhaps the largest factor affecting 



. TESTING 221 

accuracy in weighing, — granting other conditions to be right, is 
temperature. If the object to be weighed is of a lower tempera- 
ture than the balance case, it will weigh apparently more than 
its actual weight. If of a higher temperature than the balance 
case, it will weigh apparently less than its actual weight. The 
object should, therefore, be as closely as possible of the same 
temperature as that of the air in the balance case. The water 
cooled dessicator used upon the Mojonnier tester has been de- 
signed primarily to facilitate the equalizing of the temperature 
between the dishes to be weighed and the balance case. See, 
therefore, that the temperature of the water in the circulating 
system is as nearly as possible the same as the temperature of 
the balance case. 

All parts of the balance and weights should be kept free from 
dust. A cover to be placed over the balance case at night 
serves a very useful purpose. Use a camel's hair brush to remove 
the dust from both the balance and the weights. A small beaker 
partly filled with sulfuric acid should be kept in one corner of 
the balance case. Replace the sulfuric acid when it becomes 
saturated with moisture. 

Protect the balance against vibration, and see that it is in 
exact level. The air bubble in the spirit level should be in the 
exact center. This can be readily accomplished by means of the 
leveling screws under the balance case. 

The balance should be in exact equilibrium at all times. That 
is, the pointer should oscillate an equal number of divisions on 
each side of zero upon the pointer scale. If the pointer swings 
too far to the right, turn the adjusting screw upon the beam 
to the right. If it swings too far to the left, turn the adjusting 
screw to the left. 

Place object to be weighed upon the left hand pan, and the 
weights or counterpoises upon the right hand pan. Handle the 
weights with the forceps only, using the right hand. Use the 
left hand to release the beam from the support, and to raise or 
lower the balance door. The weights should be placed upon the 
pan in a systematic order, beginning with a weight that is judged 
to be somewhat too heavy. Lower weights are then tried in 
succession in a systematic order until equilibrium results. 

Upon the old style balance, adjustments under 5 or 10 milli- 
grams (depending upon the construction of the balance) are 
made by means of the rider. Keep the balance door closed 
while the final adjustment is being made. Determine the rela- 
tion between the divisions upon the rider beam, and the pointer 
scale. This relation varies with different balances, but when 



222 THE BOOK OF ICE-CREAM 

once ascertained upon a given balance it remains a constant 
value, and if applied in making a weighing, a. great deal of time 
can be saved. For example, if the pointer oscillates six divisions 
to the right of zero, and four divisions to the left, with a balance 
having a relation of .0002 gram to one division upon the pointer 
scale, the rider is moved .0004 gram to the right to bring the 
balance into equilibrium. 

Upon the Chainomatic balance, adjustments under .0500 gram 
are made by means of the screw and vernier. Determine the 
relation between the divisions upon the vernier, and the pointer 
scale. If the pointer swings too far to the right, lower the sUde, — 
if too far to the left, raise the shde. About .003 gram upon 
the vernier usually equals one division upon the pointer scale. 

Exercise great care in recording the weights. A double check 
should be made by reading both the weights upon the balance 
pan, and the weights that are missing from the set. The weights 
should be placed upon a paper near the front of the balance case, 
with the values of the weights marked upon the place where the 
respective weights are kept. Remember that one misread weight 
will spoil an entire test. Upon the Chainomatic balance read 
weights as follows: 

(a) Sum of all gram weights equals whole number. 

(b) Sum of 100 or multiple of 100 miUigrams equals first 
decimal. 

(c) Sum of 10 or multiple of 10 miUigrams equals second 
decimal. 

Out of a possible total of 100 milligrams, 50 miUigrams are ob- 
tained from the fractional weight, and 50 milligrams from the 
vernier beam. 

(d) The third decimal is obtained from the vernier beam. 
Read the value of the line just above the small upon the slide. 

(e) The fourth decimal is the value upon the shde that is in 
an exact line with any given line upon the vernier beam. 

(2) Care to give to the power unit and the water circulating unit. 

Keep the water tank well filled with water. Add about one 
quart light machine oil to the water in the tank to keep the 
water pump well lubricated. If the tester is located in a cold 
room in winter, add one gallon denatured alcohol to the tank to 
prevent freezing. 

Keep the vacuum pump chamber properly filled with the right 
kind of oil. The oil should just about reach the top of the pistons, 
as indicated by the glass upon the side, or cock upon the end. 

Give the motor proper care. It should receive the same at- 



TESTING 223 

tention as given to any motor, that is, it is to be kept cleaned 
and well lubricated. 

Should any knocks develop upon the power unit, remedy the 
same immediately. The construction is very simple, and with 
a little study, the care and operation of the power unit should 
be readily learned. 

(3) Care to give to the vacuum ovens and coolers. 

Keep sufficient mercury in the mercury well to insure good 
contact between the thermometer and the mercury well. The 
mercury well should rest directly upon the hot plate. Otherwise 
incorrect temperature will be indicated by the thermometer. 
Keep the ground joint between the hd and the oven thoroughly 
cleaned. In case that it is difficult to get the proper amount of 
vacuum, look first to this place for trouble. Sometimes it may 
be necessary to use a small amount of vaseline, but as a rule, 
the best results are obtained by keeping the ground joints thor- 
oughly clean. Be sure that the thermometer opening, and the 
openings upon the bottom of the oven are thoroughly sealed. 
It may be necessary to replace the rubber tubing at these points 
in case that leakage develops. 

Be sure to see that the cooling dessicators are kept from freez- 
ing temperatures. If the water in the cooling plates should 
freeze, it would ruin the plates. Watch the water coming out 
of the coolers, in order to be sure that the circulation is correct. 

(4) General care of the tester. 

Keep the tester clean and free from the accumulation of un- 
necessary material at all times. It is impossible to do accurate 
work if the apparatus is not in the best of condition. All ja- 
panned parts can be cleaned either with engine oil, applied to a 
clean cloth, or by washing with good soap and water. 

(5) How to clean the dishes and the glassware. 

The solids dishes should be soaked in water after the test 
has been completed, and the solids then removed by means of a 
brush suited to the purpose. They should then be thoroughly 
cleaned and dried, and placed in the vacuum oven until required 
for further use. The fat dishes should be treated with a small 
quantity of gasoline until the fat is all dissolved, and this treat- 
ment repeated a second time. Finally, the dishes are to be 
cleaned with a dry cloth, and placed in the vacuum oven until 
needed. Do not use any water upon the fat dish. 

All glassware should be washed either immediately after being 
used, or it should be placed in water until washed. Extraction 



224 THE BOOK OF ICE-CREAM 

flasks should be thoroughly washed with tap water and then 
Washed out with distilled water. If flasks become dirty, wash 
with washing powder and shot, or use washing powder with a 
brush specially designed for this flask. Clean pipettes with brush 
and water. Use washing powder, if necessary. Rinse succes- 
sively with water, alcohol, and ether, and then dry by holding at 
exhaust cock leading to the vacuum oven, or place upon pipette 
holder between fat oven and cooler. 

(6) How to heat the dishes before weighing. 

Give both the solids and the fat dishes the same treatment 
before weighing the same empty as is given to them when the 
same are to be weighed with the solids or the fat respectively in 
the same. Do not attempt to weigh dishes that have not been 
heated previous to being weighed. 

(7) How to cool the dishes. 

Transfer the solids and the fat dishes from the respective 
vacuum ovens to the respective coolers, and weigh the same as 
rapidly as possible. Weigh the solids dish with the cover on, 
and the fat dish without any cover. 

(8) How to adjust temperatures. 

The temperatures upon the two outside hot plates and the 
two vacuum ovens can be closely regulated by means of the 
rheostats. If the voltage is constant, the temperature will 
remain very near to the point desired for a long period of time 
after the rheostats have been properly adjusted. Ascertain by. 
test, just where it is necessary to hold the rheostat in order to 
get the required temperature. After this point is once ascer- 
tained, the rheostat can be set at the point required and the 
temperature allowed to come up automatically, when starting 
in the morning. 

(9) How to prepare the samples. 

Care and good judgment requires to be exercised in preparing 
samples of the various dairy products preparatory to weighing 
out samples of the same for the test. This is explained more in 
detail in the more extended descriptions following the various 
products outlined in these directions. 

(10) How to weigh samples for the fat test. 

Several methods are in use for weighing the samples for the 
fat test, depending on the product that is being tested. The 
weighing" cross with the short pipettes can be used successfully 
on a number of dairy products. Numerous advantages are 
gained by using this method, provided the product to be tested 



TESTING 225 

permits of its use. Five different samples can be weighed with 
only six weighings, and if care is taken, great accuracy is obtain- 
able. Several products can be pipetted out, taking ten grams 
and where possible, this is a very accurate method. The pipettes 
are graduated to discharge ten grams of whole milk at 60 deg. 
F., allowing 15 seconds for draining the pipette after the milk 
has all run out, and then blowing out the last drop of milk in 
the pipette. Again, when sample shows signs of separation of 
fat, the only satisfactory method is to warm up the sample until 
the fat is melted, and mix thoroughly. While stirring the well 
mixed sample, pipette out a sample into a cleaned, dried and 
weighed extraction flask suspended from the balance beam. If 
flask is wet on inside it should be weighed with cork. 

(11) Size of samples to take for the fat test. 

The size of sample to use varies, depending on the product 
being tested, and it ranges from one gram in the case of butter, 
to ten grams in the case of raw milk. See instructions in diagram. 

(12) How to add the reagents. 

The reagents should be added in the following order: Water, 
ammonia, alcohol, ethyl ether aiid petroleum ether. The burettes 
upon the dispensing cans are graduated to deliver the proper 
charge required. See instruction diagram. 

(13) How to shake the flask. 

If only one sample is being tested, this can be shaken by hand. 
As many as four samples can be shaken at one time in the shakers 
furnished with the equipment. The flask should be held with 
large bulb down and small bulb extending upward. In this 
position they are shaken vigorously lengthwise of flask. After 
shaking five or sii times, allow liquid in small bulb to run back 
into large bulb. Repeat this operation at least four times. There 
is no danger in shaking the samples too much, but rather of not 
shaking them enough. 

(14) How to centrifuge the flask. 

If only one sample is being centrifuged at a time, place a 
counterpoise upon the opposite side of the centrifuge in order to 
balance the head. Always see that there is about the same weight 
upon both sides of the centrifuge. 

(15) How to pour off the ether solutions. 

Remove the cork by twisting carefully from the flask. Pour 
off the ether solution as completely as possible, taking care not 
to allow any of the hquid under the ether to flow out of the 



226 THE BOOK OF ICE-CREAM 

flask. This can be avoided if the dividing hne between the ether 
solution and the remaining solution is carefully watched, while 
pouring off. In the first extraction, a larger amount of the ether 
solution can remain in the flask than in the second extraction. 
In the second extraction the fat dish should be placed on the 
tester top, and the operator should look down on the ether 
solution as it is being poured off, observing the point where the 
ether has been all removed. By foUowing this method, all but 
one or two drops of the ether solution should be recovered, pro- 
vided the dividing line was in the right place before pouring off. 

(16) How to bring up the dividing line. 

Inabihty to pour off the ether solution closely is due to the 
fact that the dividing line between the ether solution and the 
remaining solution is too low in the lower bulb of the flask. 
At the end of the first extraction, the dividing hne can remain 
without change, taking care to pour off the ether solution as 
closely as possible, regardless of the position of the dividing hne. 
At the end of the second extraction, remove the stopper from 
the flask, and drop in sufficient distilled water from the burette 
into the extraction flask to raise the dividing line to the desired 
point. This should be done just before pouring off the ether. 
If this procedure is followed, it becomes possible to remove the 
ether almost to the last drop. 

(17) How to evaporate the ether from the dish. 

It is important to maintain the proper temperature upon the 
outside hot plate. If the temperature is allowed to go below 
135 deg. it takes too long to evaporate the ether solution. On 
the other hand, if it rises much above 135 deg. there is danger of 
the ether boiling out over the top of the dish. If the plate is 
too hot, it is best to place only part of the dish in contact with 
the plate. We recommend that the hood be placed over the 
dishes, and that the ether fumes be blown out of the room by 
means of the blower. It is dangerous to allow the ether fumes 
to evaporate into the working room, and besides it makes it 
very unpleasant for the operator to work in contact with these 
vapors. 

(18) How to heat the fat dish in the oven. 

Do not transfer the fat dish to the vacuum oven until all 
of the ether solution has been evaporated upon the outside plate. 
If this is^not done, the contents of the dish are quite likely to 
spatter in the oven. It is very important to maintain the proper 
temperature conditions, and also the proper vacuum upon the 



TESTING 227 

fat dishes, while the same are being heated in the oven. If for 
any reason, there should be difficulty in attaining either the 
proper heat or the proper vacuum, the trouble should be im- 
mediately investigated and removed. 

(19) How to weigh the fat dish. 

The fat dishes are to be transferred from the vacuum oven 
to the cooler, in which they are to remain for seven minutes 
before being weighed. The weighing should be done as promptly 
as possible. 

(20) How to calculate the percentage of hutter-fat. 

Divide the weight of the butter-fat by the weight of the sample 
taken. Multiply the result thus obtained by 100 in order to 
arrive at the percentage of butter-fat in the sample. 

(21) Weight of sample to take for the solids test. 

This varies with the product to be tested, ranging from .25 
of a gram in the case of sweetened condensed milk, to 2 grams 
in the case of fresh milk. 

(22) How to weigh the solids sample into the dish. 

The samples can be weighed from the weighing cross, or in 
several cases it is advantageous to weigh the samples directly 
into the solids dish. 

(23) How to add water to the samples in the dish. 

For this purpose, always use best distilled water. It is well 
to run a blank upon the water to determine if it is free from solid 
matter. Reject any water that may contain any solid matter. 
Add sufficient water to make up the total volume, not to exceed 
2 cubic cantimeters. Agitate the sample with the water in the 
dish so that the remainder will be uniformly distributed over the 
bottom of the dish. 

(24) How to treat the sample upon the outside hot plate. 

It is very important to have the outside hot plate as nearly 
180 deg. as possible. If the temperature is less than 180 deg. 
there will be insufficient bubbling of the sample, so that the 
surface will be improperly broken. If a temperature above 180 
deg. is used, there is great danger of the samples spattering out 
of the dish. Heat the samples in the dish until they just begin 
to turn brown. This is one of the most important steps in the 
entire operation, and unless properly watched, an error may be 
introduced at this point. Insufficient heating may give high 
results, and over heating may give low results. 



228 THE BOOK OF ICE-CREAM 

(25) Temperature and vacuum to maintain in solids oven. 

Keep the solids oven at a temperature of as nearly 100 deg. as 
possible. This appHes to all products to be tested. Also see 
that there is at least 20 inches of vacuum upon the vacuum oven. 
If the tester is properly operated, it should be possible to main- 
tain 25 inches of vacuum at all times. 

(26) How long to retain the dish in the solids oven. 

This varies with the products to be tested. The minimum 
time is ten minutes and in the case of sweetened condensed milk, 
in order to get absolute results, it is best to dry the samples an 
hour and a half. 

(27) How to cool the solids dish. 

Transfer the dish from the oven to the cooler promptly, and 
keep the same in the cooler for five minutes with the water cir- 
culating during this time. 

(28) How to heat the solids dish. 

Always weigh the sohds dish with the dish cover upon the 
dish. Make the weighings as rapidly as possible, as otherwise 
the sample is quite hkely to absorb moisture from the atmos- 
phere. 

(29) How to calculate the percentage of total solids. 

Divide the weight of the total solids by the weight of the 
sample taken, and multiply the result by 100, which will give 
the percentage of total solids in the sample. 

(30) Order of operations in testing evaporated milk for butter-fat 

and total solids with Mojonnier tester. 
In the following outline, the procedure described is that used 
in the case of evaporated milk. The procedure in the case of 
other products is much the same, but as described in directions, 
differences may occur in the methods of weighing the samples; 
the size of the samples to use; the quantity of water or the reagent 
to add; the method of shaking, and the method of centrifuging. 
The outhne presumes that only one operator is doing the work. 
When speed is required, a helper to the operator can materially 
shorten the time required. In that case, the order of operations 
will need to be slightly modified. 

(1) See that respective dishes have been in vacuum oven at 
least five minutes while ovens are heated with vacuum on. 

(2) Place respective dishes in cooling ovens, turn pump on, 
and set bell for five minutes for solids and seven minutes for fat. 



TESTING 229 

(3) Weigh solids dish first — being careful to put cover on dish, 
and record weight and number upon laboratory report. Put 
dish back into cooling oven. 

(4) Weigh fat dish without cover. Record weight and number 
upon laboratory report, and put fat dish back in cooling oven. 

(5) Fill one 5-gram and one 1-gram pipette with milk, and 
place upon weighing cross. 

(6) Weigh above and note weight on laboratory report under 
"pipettes plus milk" column. 

(7) Transfer milk in 5-gram pipette to extraction flask, and 
return empty pipette to weighing cross. 

(8) Weigh again, and note weight in fat column under "pi- 
pettes." 

(9) Put above weight in solids column of laboratory report, 
also under heading of "pipettes plus milk." 

(10) Transfer milk from one gram pipettes to the weighed 
solids dish, and return pipette to weighing cross. 

(11) Place weighing cross upon balance, weigh, and record 
weight under the heading "pipettes." 

(12) Add equal volume of distilled water to solids dish, dis- 
tribute evenly, and place on solids hot plate. 

(13) When evaporation has taken place, put in solids oven. 

(14) Turn on vacuum and set bell for ten minutes. 

(15) At this point take extraction flasks with milk in and 
make first extraction, centrifuge and pour ether into fat dish. 

(16) Make second extraction, same as 15. 

(17) During above period solids bell will ring and solids dish 
should be transferred to cooling oven, and bell set for five minutes. 

(18) As soon as ether has evaporated, place dish in fat oven, 
turn vacuum on, and set bell for five minutes. 

(19) When solids bell rings, weigh dish and record weight. 

(20) When fat test bell rings, transfer to coohng oven, and 
set bell again for seven minutes. 

(21) Complete subtractions on laboratory report. 

(22) Weigh fat dish, turn pump off, and finish calculations. 

(23) From tests obtained, determine what material to add to 
standardize batch. 



174. Testing evaporated, sweetened condensed, bulk 
condensed milk ice-cream (mix or melted), for fat 
and total solids. — The process is outlined in the follow- 
ing steps: 



230 THE BOOK OF ICE-CREAM 

(1) Wash solids dishes with warm water and fat dishes with 
gasoline. Dry with a towel and place into heated vacuum oven 
for five minutes, with vacuum on. At the end of five minutes, put 
these dishes into cooler and with pump still running, keep them 
there for five minutes before weighing. Do not turn off motor 
until last dish is weighed out of coohng chamber. 

(2) While dishes are being heated and cooled, wash pipettes 
with water, alcohol and ether, and dry by applying vacuum at 
exhaust cock upon tester. Always use clean and dry pipettes 
for each different sample. Aim to clean pipettes as well as all 
glassware, immediately after using. 

(3) It is very important to keep the extraction flasks clean. 
Wash these with warm water immediately after extraction is 
finished. Wash with washing powder and shot when necessary. 

(4) Keep solids dishes in cooler for at least five minutes, weigh 
accurately to .0001, using the proper counterpoise. Weigh solids 
dishes with cover on. Keep fat dishes in cooler for seven minutes 
before being weighed. Fat dishes do not have cover. 

(5) Use pipettes as follows: Fill 5-gram pipettes up to 5 
gram mark for butter-fat and 1 gram pipette up to 1 gram 
mark for total solids. If duplicates are to be run, fill two pipettes 
from the same sample. As pipettes are filled, place lower end 
into cleaned and dry rubber tubes which are pressed upon knobs 
at ends and center of weighing cross. Either five or less samples 
for butter-fat or five or less for total solids may be pipetted 
out. 

(6) Weigh the cross with the pipettes containing the milk on 
chemical balance accurately to .0001 gram. Run milk from 
pipette into proper flask, or 3 inch dish if making solids test. The 
pipettes may be distinguished by the number upon each cross. 
Replace pipette and weigh again. Difference in weight gives 
weight of sample. Repeat until all samples are run into proper 
flasks, and into weighed solids dishes if solids are determined 
along with the -fat. 

For fat in sweetened condensed milk use a 5-gram sample. 
The 5 -gram pipette delivers approximately 5 grams between the 
5 gram mark and the base of the bowl of the pipette. 

Some operators prefer to mix 200 grams of sweetened con- 
densed milk with 200 grams of water, weighing these carefully 
upon a Harvard trip scale sensitive to .1 gram. In this case, 
care must be exercised to obtain the exact weight of both milk 
and water^and to stir these thoroughly with glass or metal rod 
before taking sample. A tall tumbler, a one-pound bottle or a 
quart cup, make good containers in which to make mixture. A 



TESTING 231 

10-gram sample of this mixture is used. This is best weighed 
out by using two 5-gram pipettes on weighing cross. 

For total sohds, weigh out 3^ (.5000) to M (.7500) gram of 
this mixture. If the undiluted milk is used, take as nearly i^ 
(.2500) gram as possible. 

For regular 8 per cent plain bulk condensed milk, use same size 
samples and treat same as evaporated milk. For 12 per cent 
superheated condensed milk, mix 100 grams milk with 300 grams 
water upon Harvard trip scale. Weigh 10 gram sample of this 
mixture into flask for fat, and a 2 gram sample into solids dish 
for solids. Multiply percentages obtained by 4 for correct per- 
centages, when a 1 to 4 dilution is made. 

175. Fat determination. — The following steps should 
be followed when making the fat test. 

(1) Remove flask from holder and run 4 cubic centimeters 
water (one charge on water burette) into each flask. Be careful 
not to add more. Shake well until all of sample is mixed with 
water. This can be done without inserting cork 

For sweetened condensed milk, if not diluted with water, add 
8 cubic centimeters of hot water with a pipette. To get hot 
water, place fat dish filled with distilled water upon solids plate. 
If sweetened milk has been previously diluted with water and a 
10 gram sample has been used, it is not necessary to add water. 
It is very necessary to shake the flasks containing the sweetened 
condensed milk very thoroughly after the addition of each re- 
agent. Sweetened condensed milk requires more shaking than 
any other liquid milk product. 

(2) Before replacing flask into holder, add 13^ cubic centi- 
meters C. P. ammonia, one charge on burette. Shake well so 
that all of sample is well mixed with ammonia. This can be 
done without inserting cork. 

(3) Add 10 cubic centimeters of 95 per cent alcohol. Insert 
cork, twisting cork in firmly, using best quality corks only. Re- 
place the flask into flask holder. Shake thoroughly, and see 
that no milk adheres to any part of flask undissolved. In case 
particles of milk stick to side of flask, shake thoroughly until 
these are washed away. It is of utmost importance to shake 
thoroughly at this point. 

(4) Add 25 cubic centimeters ethyl ether, insert corks and 
shake vigorously, lengthwise of flask, with liquid in large bulb 
of flask, and small bulb extended upward. Stop shaking at end 



232 THE BOOK OF ICE-CREAM 

of five seconds until all liquid has run into large bulb and repeat 
vigorous shaking for four five-second periods. 

(5) Add 25 cubic centimeters petroleum ether and shake in 
same way. 

(6) Place extraction flasks into centrifuge and whirl for thirty 
turns at speed of about 600 revolutions a minute. Have centri- 
fuge balanced with small oil sample bottles furnished with 
tester. Double time for sweetened condensed milk. 

(7) Place four 3}^ inch dishes in line on shelf adjoining hot 
plate, keeping them in order in which their weights were posted 
on record sheet. Aim to have numbers on flasks correspond with 
number of dishes. 

(8) Pour ether extraction above dividing fine into proper 
dishes and slide dishes over onto hot plate which should be held 
at a temperature of 135 deg. C, as indicated by thermometer 
inserted in nickel plated mercury well. Be careful to pour off 
no solid matter. Cover dishes with hood. 

(9) Repeat the extraction, shaking first to prevent formation 
of precipitate, then adding successively 5 cubic centimeters of 
95 per cent alcohol, then 25 cubic centimeters ethyl ether and 
then 25 cubic centimeters petroleum ether, and shake vigorously 
after the addition of each of above three reagents for four five- 
second periods. 

(10) Whirl in centrifuge for thirty turns. 

(11) Move aluminum dishes back upon shelf adjoining hot 
plate, when almost dry, and pour the second extraction into 
proper dishes. Never pour extraction into hot dish. Remove 
dish from hot plate as soon as ether is all evaporated. 

(12) When all of ether has evaporated, place dishes into 
vacuum oven which should have a temperature of 135 deg. C. 
Keep them there for five minutes after the vacuum gauge shows 
at least 22 inches of vacuum. 

(13) Place dishes into cooler for seven minutes, with pump 
outfit running. See that water is running through cooling plates. 

(14) Place counterpoise for dish and the approximate weight 
for fat on right hand balance pan. 

(15) Transfer dish to left hand balance pan and weigh quickly 
to 0.10 milligram (0.0001 gr.). 

(16) Weight of fat divided by weight of sample taken, multi- 
plied by 100 represents percentage butter-fat. 

176. Total solids determination. — The steps in making 
the test are as follows: 



TESTING 233 

(1) The temperature of the hot plate in the solids vacuum 
oven must be 100 deg..C. The temperature of the outside solids 
plate must be 170 deg. to 180 deg. C. 

(2) To weighed milk in solids dish, add about 1 cubic centi- 
meter water and distribute mixture evenly over bottom of dish, 
immediately after weighing. For sweetened condensed milk, 
use hot water, or place momentarily on hot plate and distribute 
evenly over dish by shaking sidewise very carefully after cold 
water is added. 

(3) Place not more than two dishes at once upon hot plate, 
which must be perfectly level. Allow all visible moisture to 
evaporate. During the evaporation turn the dishes around with 
crucible tongs slowly so as to produce an even boiling over the 
whole bottom surface of the dishes. The dishes must be watched 
carefully during the evaporation. This step should require not 
more than two minutes. The end point is reached when bubbling 
and crackling ceases and sample shows first trace of brown. 
Vigorous boiling without spattering and complete evaporation 
are fundamentally essential. 

(4) Place dishes into vacuum oven which must be at 100 
deg. C. and turn on the vacuum. Heat for ten minutes. In the 
case of sweetened condensed milk keep it for ninety minutes in 
vacuum oven, or heat for twenty minutes and deduct 30 per cent 
from result. The gauge should register not less than 22 inches of 
vacuum. If for any reason you cannot obtain at least 22 inches of 
vacuum, then leave your dishes in oven for twice the regular 
time. 

(5) Remove from oven and place into cooler. Allow dishes to 
cool for five minutes. 

(6) Weigh dishes with covers on, being careful to weigh quickly 
and very exactly. 

(7) Weight of dry solids divided by weight of milk taken, 
multiplied by 100, represents percentage total solids. 

177. Testing butter. — Both the fat and the moisture 
may be determined by this test. The sample may be 
prepared in either of two ways: 

Method I. Remove about one-half pound butter from the 
different parts of the churn or tub with a butter trier, and put 
this into wide-mouthed bottle or Erlenmeyer flask fitted with 
rubber stopper having a thermometer in the center of the stopper, 
and reaching down into the mass of butter. Heat bottle in hot 



234 THE BOOK OF ICE-CREAM 

water until thermometer reaches 40 deg. C. or 104 deg. F. If 
this temperature is not exceeded, there is very httle danger of 
the butter-fat spreading rapidly from the curd. Shake vigorously. 
Method 11. Another very satisfactory method of preparing 
butter for sampling is to put butter as it comes from churn or 
tub into Mason jar, beaker, glass tumbler, or wide-mouthed 
bottle, any of which may be covered tightly to prevent evapora- 
tion. Allow these to stand in warm room or in warm water 
until the butter is soft enough so that it may be stirred thor- 
oughly with table knife, spatula, or a mechanical stirrer. At 
temperature of about 75 deg. to 80 deg. F. butter stirs into a 
waxy form from which water or casein will not separate. In 
this form, it is put into boat or flask to be weighed. 

Fat determination: 

(1) If sampling method I is used, measure (about) 1 gram 
into weighed butter boat. Weigh quickly and insert boat into 
flask. If sampHng method II is used, put about 1 gram of the 
butter sample into weighed boat, weigh quickly, and insert into 
extraction flask. 

(2) Remove flask from holder and add to extraction flask 9 
cubic centimeters hot water from aluminum dish placed on fat 
plate. Mark 10-gram pipette up to 9 cubic centimeter and use 
this for measuring hot water. Shake vigorously so as to mix 
butter thoroughly with water. 

(3) Before replacing flask into holder, add 13^2 cubic centi- 
meters C. P. ammonia and shake thoroughly, making sure that 
butter is thoroughly mixed with ammonia. 

(4) Add 10 cubic centimeters of 95 per cent alcohol. Insert 
cork. Replace flask into flash holder. Shake flask thoroughly 
with cork inserted. Use best quality corks only. 

(5) Cool flask by running cold water over lower end of ex- 
traction flask, if flask is very hot. This is not ordinarily neces- 
sary. 

(6) Add 25 cubic centimeters ethyl ether. Insert corks, shake 
vigorously until all butter is dissolved out of boat. Then add 
25 cubic centimeters petroleum ether and repeat operation. 

(7) Centrifuge flasks, turning handle thirty turns after centri- 
fuge has reached a speed of about 600 revolutions a minute. 

(8) Pour off extractions into proper weighed 33^ inch aluminum 
dishes. Repeat above extraction, adding successively 5 cubic 
centimeters of 95 per cent alcohol, then 25 cubic centimeters of 



TESTING 235 

each ether. Excepting for very accurate work, a third extraction 
is not necessary. The second extraction will remove all but .10 
to .15 per cent of the butter-fat. For factory control work this 
would be a good margin of safety. 

(9) Evaporate off ether at 135 deg. C. on "fat plate," and 
when all of ether is off, dry fat in fat oven held at 135 deg. C. 
for five minutes after the vacuum has reached at least 22 inches. 

(10) Cool, weigh, and calculate percent jL^e butter-fat as in reg- 
ular fat test. 

To determine moisture in butter: 

If sampling method I is used, keep butter at 140 deg. F. and 
mix thoroughly and while well mixed, weigh 1 gram into the 
sohds dish as quickly as possible to prevent evaporation. _ If 
second method of sampling is used, weigh 1 gram of butter into 
the sohds dish. Heat on hot plate at 180 deg. C. until foam- 
ing ceases, and then place in vacuum oven held at 100 deg. C. 
for seven minutes. Cool, weigh and calculate percentage sohds; 
100 less this figure represents percentage moisture. 

178. Testing fresh milk, skim-milk, whey, buttermilk 
for fat and total solids. — The fat test is made as follows: 

(1) Use the 10 gram pipettes for measuring out 10 grams of 
milk into cleaned but not necessarily dried Mojonnier extraction 
flask. Use only 10 gram pipettes furnished with tester and do 
not use 10 cubic centimeter pipettes. The pipette is graduated 
to dehver 10 grams of milk, after allowing all milk to run out 
and letting it drain for fifteen seconds longer, then blowing gently 
to remove last drop. The pipette must be perfectly clean and 
dry before being used. Wash frequently with sulfuric acid, 
water, alcohol, and ether to insure having a clean pipette. 

(2) Make extractions exactly as in test for butter-fat in con- 
densed milk, excepting that no water need be added, and in 
second extraction only 15 cubic centimeters of each ether need 

be used. 

(3) Percentage butter-fat is obtained by multiplying the 
weight of the extracted butter-fat by 10. 

(4) If any of these products have soured badly, double the 
quantity of ammonia in the regular extraction and shake until 
all particles are dissolved. 



236 THE BOOK OF ICE-CREAM 

Total solids determination: 

Determining total solids as in evaporated milk, excepting that 
a 2-gram sample is weighed out, and no water need be added 
to spread the milk over the bottom of the dish. 

179. Testing powdered milk, cocoa, malted milk and 
milk chocolate for fat and total solids. — 

Mix the sample thoroughly, making sure that it is sufficiently 
pulverized, and representative of the entire lot to be tested. In 
the case of milk chocolate, pulverize the sample very thoroughly, 
in a close grained mortar. Transfer the pulverized sample 
promptly to a sealed jar. Mix before removing portions for 
testing. 

Butter-fat determination: 

(1) Weigh out rapidly, to prevent absorption of moisture 
from the air, about 1 gram of milk powder into butter boat. In 
case of malted milk, milk chocolate and cocoa, weigh out a 0.5 
gram sample. 

(2) Add 8.5 cubic centimeters of hot water to flask. Insert 
cork. Heat flask in water boat, and shake thoroughly until 
the sample is well mixed. 

(3) Add 1.5 cubic centimeters (one charge) ammonia, and 
shake thoroughly. 

(4) Add 10 cubic centimeters of 95 per cent alcohol. Shake 
thoroughly. Cool the flask, if necessary. 

(5) Continue the extraction exactly as directed under the 
butter-fat determination, paragraphs 4, 5, 6, and 7, inclusive. 

Total solids determination: 

Use .3000 gram sample. Add 2 cubic centimeters distilled 
water to the sample in this dish. Otherwise continue the deter- 
mination exactly as directed under total solids determination 
in cheese. 

180. Testing cream for fat and total solids. — 

Mix sample thoroughly in the container.' If the cream has 
been homogenized, it can be weighed with the weighing pipettes 
as described under 5, page 230 of these directions. If the cream 



TESTING 237 

is churned or lumpy it has to be heated until the fat is all just 
barely melted, and the entire mixture is uniform. Cream is a 
product that is subject to many variations in composition, 
degree of acidity, and physical condition. For these reasons, 
the operator needs to exercise the best judgment possible. The 
method of operation may require, at times, shght modification, 
depending on the condition of the sample. 

Butter-fat determination: 

(1) For cream testing under 15 per cent butter-fat, take about 
a 2 gram sample, using 2-gram pipette. For cream testing over 
15 per cent butter-fat take a 1-gram sample. If practicable, 
weigh out of pipette as described under 5, page 230.^ Otherwise 
weigh the sample in the butter boat, or directly into the ex- 
traction flasks, which were previously weighed. 

(2) Remove flask from the holder and add enough water to 
make a total of 10 cubic centimeters. Insert cork and mix 
thoroughly. 

(3) Before replacing flask in holder, add 1.5 cubic centimeters 
(one charge) of ammonia. If the cream is sour add 3 cubic 
centimeters of ammonia. This is very important. 

(4) From this point to the end of the test, continue as stated 
on page 231, beginning at paragraph 2 to paragraph 16, inclusive. 
At the end of the second extraction it may be necessary to add 
quite a little more alcohol, in order to bring the dividing Hne up 
to the required height. 

Total solids determination : 

Use a 1.0 gram sample. Add 1 cubic centimeter distilled 
water to the sample in the dish. Otherwise proceed exactly as 
directed in sections 3 to 7 of page 233. 

181. List of precautions to observe in operating Mo- 
jonnier tester. — 

(1) Before the reagents are put into the cans, be sure that 
the cans are thoroughly cleaned by washing all parts, first with 
warm water, then alcohol and then ether. Every third or fourth 
time cans are filled, empty out last portion of reagents, and use 
for cleaning purposes. 

(2) The bottoms of all dishes should be kept as flat as possible. 
Any bulging may be worked out by resting dishes upon marble 



23S THE BOOK OF ICE-CREAM 

plate in front of balance, rubbing entire bottom surface with 
thumbs. Operator should observe this every time dishes are 
cleaned. This is very important. 

(3) The calcium chloride in the coolers should be changed 
every three or four weeks. The same calcium chloride may be 
used over and over by drying the used calcium chloride in tin 
dishes placed upon hot plate held at 135 deg. C. for at least five 
hours. 

(4) The bottles should be whirled in the centrifuge until the 
ether extraction is perfectly clear. About thirty turns at a normal 
speed are to be recommended. For sweetened condensed mill<: 
this time must be doubled. 

(5) Be sure to keep extraction flasks perfectly clean. Wash 
often with sulfuric acid and washing powder, if necessary. If 
particles cling to the sides put in small shot, washing powder and 
hot water, and shake thoroughly. 

(6) Keep temperature regulated as nearly to standard tem- 
perature as possible. 

(7) Never pour off extraction into a hot dish._ Remove dish 
from plate before second extraction is run into dish. 

(8) Be careful to pour off ether into dishes slowly at first and 
gradually increase stream until full stream is running. 

(9) In using weighing pipettes, make sure that neck of flask 
is free from water when pipette is inserted. 

(10) Always use clean and dried pipettes. 

(11) If the samples for solids have to stand for any length of 
time, add the water just as soon as they are measured out, other- 
wise there is a tendency to dry and a good mixture with water 
cannot be obtained. Keep dishes upon marble plate beside the 
balance, and not on hot plate support. 

(12) Redistill ethyl ether and petroleum ether, unless they 
are known to be pure. This is unnecessary if these are bought 
from a reliable firm. 

(13) Make sure that water is always running through cooling 
plate. Watch pipe back of cooler. If tester is located in cold 
room in winter, add a gallon of denatured alcohol to tank to 
prevent freezing. 

(14) Always aim to weigh empty dishes just before you are 
ready to use them. It is not advisable to weigh them a long time 
before they are used. 

(15) It is fundamentally important to see that weights are 
read and, posted rightly. Operator should- keep his weights in 
systematic order upon balance pan. When a reading is taken, 
it should be checked at least three times. Learn to make weigh- 



TESTING ^ 239 

ing absolutely correct. One figure misread may cost a month's 

salary. . ^ , 

(16) Every operator should from time to time have a sample 
checked by a thoroughly reliable laboratory. Mojonnier Bros. 
Company, Chicago, Illinois, maintain such a laboratory exclu- 
sively for this purpose. Charges very, moderate. 

If results on fat are high as compared with check results, the 
cause may be one of the following: 

(a) Not keeping bottoms of dishes flat. 

(b) Improper shaking and centrifuging shown by non-fatty 
residue in dish. 

(c) Improper reagents (if in doubt run test upon reagents sub- 
stituting water for milk). 

(d) Temperature in fat oven too low. 

(e) Dirt has gotten into dish after ether was poured into it. 

(f) Improper reading or posting of weights. Weights have 

lost weight from use. . , , i ix ^t. 

If results on fat are low as compared with check results, tne 
cause may be one of the following: 

(a) Leaky corks. Use best corks obtainable. 

(b) Insufficient shaking. 

(c) Adding too much water. 

(d) Having dividing fine too low, so that too much ether is 
left behind. If such is the case, add more alcohol to bring line 
to the proper height, before pouring off, or make a third ex- 
traction. 

(e) Too high temperature in vacuum oven. 

(f) Not having water running through cooler. Tank must be 

kept filled. 

(g) Improper reading or posting of weights. 

If results on total sohds are too high, as compared to check 
results the cause may be one of the following: 

(1) Bottoms of dishes are not kept flat. 

(2) Evaporation upon solids plate has not been carried far 
enough. Be sure to manipulate dish so that vigorous boiling 
takes place upon the entire surface of the bottom of the dish 
Do not remove dish until all visible moisture is off or until hrst 
trace of brown coloration appears. . 

(3) Improper reading or recording of weights. Weights have 

lost weight from use. , , i • r, j 

(4) Dirt has fallen into dish after sample has been weighed 

into it. . 

(5) Temperature in vacuum oven is too low. 

(6) Vacuum is not up to standard. 



240 THE BOOK OF ICE-CREAM 

If results on total solids are too low, the cause may be one of 
the following: 

(1) Sample is browned too much upon outside hot plate. 

(2) Temperature in vacuum oven is above 105 deg. C. 

(3) Milk spattered from dish. This will not happen if tem- 
perature is kept at 180 deg. C. 

(4) Improper reading or recording of weights. 

(5) Water is not running through cooler. 



MOJONNIER OVER-RUN TESTER 

A simple test for determining the percentage of swell 
or over-run has been devised by Mojonnier Brothers. 
This can be used in connection with the freezing to obtain 
a uniform over-run on each freezer of ice-cream. The 
tester is shown in Fig. 76. 

The over-run tester should be placed in the freezer- 
room between two freezers, as it is designed to work both 
sides. The base or pedestal should be levelled carefully 
as follows: Place level on surface just over the pedestal 
cabinet. This should be levelled in both ways. When 
pedestal is levelled, fasten securely with lag screws or 
bolts to floor, using same method employed in fastening 
base of freezers to floor. 

In large freezer-rooms when a girl makes over-run 
tests and records the over-run and advises the freezer 
man when to draw, one over-run tester for each six freezers 
will suffice. When the freezer man makes his own tests 
and records, one over-run tester will suffice for each four 
freezers; that is, two freezers on either side. 

182. Adjusting cups for mix. — The cup should be ad- 
justed for every batch, except in some ice-cream plants, 
where the butter-fat and total solids are carefully stand- 
ardized.^ In such cases, after the cup has been adjusted, 
it will require very little, if any, adjusting thereafter. 



TESTING 241 

For instance, if the mix is standardized to 8 per cent butter- 
fat and 33 per cent total solids and is kept at this standard 
by careful testing, no adjustments need be made. The 
threads of the cup are slightly greased with vaseline be- 




FiG. 76. — Mojonnier over-run tester. 

fore being shipped. They should be slightly greased 
occasionally, to facilitate free action. 

The following directions should be followed: 

See that the telescopic base of over-run cup is unscrewed 

as far as is necessary to hold 500 gram mix (counterpoised 

by the per cent weight. This will be a little less than 

one pint). Place empty cup in suspended cup holder. 



242 THE BOOK OF ICE-CREAM 

Fill dipper with the finished mix from hopper, or pipe 
line, and pour in the mix until dial indicator points to per 
cent. The mix should contain all ingredients, namely, 
sugar, gelatine, and the like. 

Remove the cup of mix from the scale, place the slotted 
base on the metal cleat underneath the weighing frame. 
Adjust this telescopic base by turning cup around so that 
the top of mix comes exactly even with the top of the cup. 
Carefully lock the base of the cup in position by means 
of the knurled locking ring. 

After the cup is adjusted, empty the mix back into the 
hopper over the freezer, and rinse out the cup in a pail or 
five-gallon can of warm water, making ready for the over- 
run determinations. There is now a fixed relation between 
the capacity, and the weight of the cup and the markings 
on the scale dial. 

183. Actual operation. — ^A heaping cup of frozen ice- 
cream should be drawn from the freezer, scraping excess 
off with the broad plated knife, to an even level. Cup is 
placed in suspended weighing frame. The dial indicator 
will immediately show the percentage of over-run. If it 
points to 60, it indicates 60 per cent over-run; if to 90, 
90 per cent and so on. Two operators may use the same 
over-run tester at the same time if desired, one working 
from either side. Repeated use of the tester will enable 
the operator to handle the work with considerable dex- 
terity and speed. 

184. Controlling the over-run. — While there is no set 
rule that can be followed regarding the control of over-run, 
the following may offer some suggestions to operators : 

There are two approved methods for operating the Mo- 
jonnier ice-cream over-run tester. 

1. By a special tester, either a girl or a man whose sole 



, TESTING 243 

duties are to test the frozen ice-cream carefully, and notify 
the freezer man when to draw the ice-cream from the 
freezers, that. is, after it has reached the desired over-run. 
In this method, one operator may run six freezers for 
each over-run tester. 

2. When the freezer man makes his own tests just be- 
fore drawing the ice-cream from the freezers. In order 
properly to control the over-run, there should be one 
tester for each four freezers. 

The first method applies particularly when from one 
to eight freezers are used. The second method applies to 
large plants having more than eight freezers in use, and 
where there is difficulty in procuring adequate help, or 
when it becomes necessary to change help frequently. 

First operation: When starting to freeze a new batch, see that 
over-run cup is adjusted as described. 

Second operation: Draw exactly five gallons of cream into the 
hopper above freezers when using a ten-gallon freezer. (If larger 
freezers are used, draw a volume into the hopper equal to one- 
half rated capacity of freezer.) It is well to graduate and mark 
very plainly the one-half capacity upon the hopper of the freezer. 

Third operation: Run mix into the freezers as usual, filling all 
four freezers, while the freezers are running. 

Fourth operation: Turn on the brine and continue whipping. , 

Fifth operation: The brine temperature and the brine pressure 
should be such that about 100 per cent over-run can be obtained 
with the brine turned off, and by turning on the brine again, 
will result in the over-run going down too quickly. If turning 
on the brine after whipping does not reduce the over-run, it is 
an indication of poor brine temperature. In that case, shutting 
down the machine for a short time is advisable, in order 'to get 
the brine temperature down to a point where freezing may be 
done efficiently, and the yield or over-run kept under proper 
control. 

It is well to regulate the proper pressure according to the 
brine temperature until the desirable over-run is obtained. 
There is a fixed relation between these two factors, and by using 
the over-run test as a guide, it is possible to adjust the pressure 
to the temperature necessary to obtain the best over-run. 



244 THE BOOK OF ICE-CREAM 

Brine valves on each freezer should be kept in good condition 
so that when they are turned off, there is no flow of brine through 
the freezer. A leaky valve may cause the over-run to refuse to 
go up, due to the low temperature of the batch, thus preventing 
proper whipping. Whip with the brine on until the ice-cream 
is quite stiff. At this point, take test for over-run. If a satis- 
factory over-run is procured, turn on brine and draw off batch. 
If a satisfactory over-run has not yet been obtained, turn on the 
brine and continue whipping until by repeated test, the proper 
over-run is obtained. After the freezer is emptied, this operation 
is repeated in the same way. 

Many operators make it a point to draw off ice-cream when 
over-run shows between 90 and 100. Ice-cream with over-run 
of more than 110 per cent is usually not a satisfactory commer- 
cial product. 

Sixth: Record under the proper freezer number on the freezer- 
room blank, the final over-run test indicated when the cream 
is drawn. Do not record any but the final result. This will 
form a valuable check on the volume of ice-cream as recorded 
in the hardening-room. It is possible in this way for the manager 
of the plant to obtain an accurate idea of how careful the over- 
run has been controlled. 

Operating under the second method, or when a girl makes the over- 
run tests. 
Under this method, the helper in the freezer-room should not 
draw off the ice-cream until it has been carefully tested and con- 
trolled. One girl can test and control the over-run of ice-cream 
from six freezers with one over-run tester, having three freezers 
on each side. She can keep close watch of the frozen cream 
through the peep hole in top of the freezer. As soon as the cream 
seems to be of the proper consistency, a test of the over-run 
should be made. 

Principal causes of variation in over-run: 

The following factors influence the over-run: 

(1) Milk solids in the mix (8) Brine temperature 

(2) Butter-fat in the mix (9) Time of freezing 

(3) Speed of freezers (10) Amount of mix drawn into 

(4) Proper ratio between solids freezer 

not fat and butter-fat (11) Blades of dasher dull or 

(5) Age of mix worn 

(6) Acidity of mix (12) Shpping of belt 

(7) Brine pressure (13) Leaky brine valves 

(14) Type of freezers 



Product 



Table XIII 
Summary of Methods of Making Fat Tests and Total Solids Tests with the Mojonnier Tester 



Product 


How to 


How to 
fat sample 


Sizcof 
sample to 
take for 
fat test 


REAQE>fT8 TO ADD, AND HOW TO SHAKK. 


How 
/uge 


Reagents to 
water after c 


CTION — Use no 
entrifuging as i 


idicated. A few 


How long 
to centri- 
fuge 


1 

How to 


to keep 
samiile in 
oven and 
cooler in 


Howto 

weigh solid 

sample 


.S(--e of 
sample 
to take 
for solids 


Amount 

M add to 
sample 
in dish 


Hoio 


tested 


Water 


A>nmo7!M 


Alcaluil 


Ethyl 
ether 


Petroleum 
ether 


make a much more distinct dividing line. 


satffein 




Alcohol 


Elh:,l 

ether 


Petroleum 
ether 


oven and 
cooler 


Frc3k milk 


Mix 
thoroughly 


Measure with 
10 gram 
pipette. 
Drain pipette 
15 seconds 


10 grams 


No water 


1.5 cc. 
Shake 
thoroughly 


10 c.c. 
Shake hall 


Add 25 c.c. 
Shake 
for one 
minute 


Add 25 c.c. 
Shake 
tor one 


30 turns 


.Shake 20 sec. 


15 c.c. 
Shake 20 sec. 


15 c.c. 
Shake 20 sec. 


30 turns 


If necessary to 5 _,:„ :^ 
raise di\'iding o,,„„ '( 
line, add the , .,=0 ^ 
necessary 7 „:„ ■ 
distilled water ' ,S „■ , 


Use cross and 
2 gram pipette 
or pipette 
about 2 grams 
diroctb- into 
dish upon 
balance 


2 grams 


none 


10 min. in 

lOO" C. 
5 min, in 
cooler at 
room temp. 


Skim-milk 


Mix 

thoroughly. 
Get represen- 
tative sample 








1,5 c.c. 
Shake 
very thor- 
oughly 






























Wkeu 










1.5 c.c. 
Use more 
if whey is 
acid. Shake 
thoroughly 






























BuUermilk 


Mix 
thoroughly 








1.5 c.c. 
Shake 
thoroughly 






























Evaporated 
milk 


Shake in can 

very 

thoroughly 


Use cross 
and 5 gram 
pipette 


Weigh 
about 
5 grams 


Use 4 c.e. 

Shake 

thoroughly 














25 c.c. 
Shake 20 sec. 


25 c.c. 
Shake 20 sec. 








Use cross and 
1 gram pipette, 
or pipette 
about 1 gram 
directly into 
dish upon 
balance 


1 gram 


lc.„. 




Bulk UTl- 

awectened 
condensed 
milk 


Mix very 
thoroughly. 
Get represen- 
tative sample 






































Bulk, extra 

sweetened 
condenaed 

milk 




Use cross and 
one S gram 
pipette 


About 
3 grams 


7 c.c. 
Shake 
very thor- 
oughly. 
Hot water 
preferred 


Shake ' 
very thor- 
oughly 


10 c.c. 
Shake one 




















Use cross and 
5grampipetto, 
or pipette 
about 5 grams 
directly mto 
dish upon 
balance 


50 gram 


2C.C, 




Sweetened 
condensed 
milk 


Proceed 

without 

diluting. 

Mix 

thoroughly 


Use cross and 
5 gram sample 


About 
5 grams 


8 c.c. hot 

Shake 
until thor- 
oughly 


Shake' 
thor- 
oughly 








60 turns 








GO turns 






Use cross and 
pipette, or 
pipette about 

directly into 
dish upon 
balance 






no min. 

lOO" C, or 
20 min. and 
dciliict ,.30% 
from lotal. 

cnolcr'at 


Ice-cream 


Mix 

thoroughly. 
Heat slightly 

to melt fat 


Use cross and 
5 gram pipette 
and weigh rap- 
idly or weigh 
directly into 
flask 




Oc.c. 
Shake 
thoroughly 










30 turns 








30 turns 






Use crusts ntid 
1 gram pipette, 
or pipette 
about 1 gram 
directly into 
dish upon 
balance 


Igram 


Icc. 


10 min. in 

joo"c. 


Cream 
teatino 
less than 
£5% b. f. 


Mix 

thorouRhly. 
Heat slightly 

to melt fat 


Use weigh 
cross with 
2 gram pipette. 
If necessary 
use boat or 
weigh directly 


About 

2 grams 


e c.c. 
Shake 
thoroughly 


1.5 c.e. 
Use 3.0 c.c. 

Shake 
thoroughly 


10 c.c. 
Shake liajf 
minute 


Add 25 c.c. 
Shake 
tor one 


Add 25 c.c. 
Shake 
for one 


30 turns 


Sc.c. 

Shake 20 sec. 


Rha'ko'20 sec. 


25 c.c. 
Shake 20 sec. 


30 turns 


raise dividing 
line, add the 

distilled water 
just before 
pourin? off 


oven at 
135° C. 
7 min. in 
cooler at 
room temp. 


1 gram pipette, 
or pipette 

directly into 
dish upon 
balance 




1 c.c. 


oven at 
100° C. 

cooler at 
room temp. 


Cream 
teslino 
more than 
S5% b.f. 






About 
1 gram 


Sc.c. 
Shake 
thoroughly 
























Use cross and 
1 gram pipette, 
or pipello 
about half grnni 
directly into 
dish iipon 
balance 


~ 






Malted milk 


Mix 

thoroughly. 
Get represen- 
tative sample 


Use butter 
boat, or weigh 
directly 
into flask 


.5 gram 


10 c.c. hot. 
Shako 
thor- 
oughly 


1.5 c.c. 
Shake 
very thor- 
oughly 






















Weigh enmplo 
directly into 
dish upon 
balance 


.30 gram 


2 c.c. 


"00" C. 

cooler at 
mom Icmp. 


Milk 

chocolate 


Pulverize in 
close grained 

mortar. 
Transfer to 






































Cocoa 


Mix 

thoroughly. 
Get represen- 






































Cheese 


tzB^' 




1 .0 gram 




























50 gram 


.5 c.e. 




Butter 


Sec 

detailed 

directions 


Use butter 
boat 




























Igram 


none KJ0°°C.. 
cooler at 

10 min. in 


Skimmed- 
milk 


Pvdveri7.e in 
close grained 
mortar. 
Tranafer to 
sealed jor 


Use butter 
boat or weigh 
directly 
into flask 


About 
1 gram 


S..') c.c. 
Hot water. 
Shako 
thoroughly 


1.5 c.c. 
Shake 
thoroughly' 


10 c.c. 
Shake one 
minute 










15 c.c. 
Shake 20 sec. 


15 c.c. 
Shake 20 sec. 










30 gram ' 


c.c. 


00° C. 
min. in 
oolcr at 
00m temp. 












Whotr- 
,ni!k 






















Shake 20 sec. 


25 c.c. 
Shake 20 sec. 



























TESTING 245 

185. Savings and economies. — ^By using the Mojonnier 
over-run tester intelligently, the operator can insure the 
management an even uniform product from day to day, 
at an economical cost. Many plants have increased their 
over-run test, and at the same time turned out a more 
satisfactory product. 

Success depends on how carefully and consistently the 
tester is operated. The operator can soon make himself 
very valuable to the management of the ice-cream factory. 
The tester removes guess-work from the freezer-room 
practice and places it on a scientific basis. 



CHAPTER XV 
MARKETING AND BUSINESS MANAGEMENT 

The question of a market for the product is most 
vital. If the ice-cream is manufactured and a market 
cannot be found, the business is a failure. This is more 
especially true with ice-cream than the other dairy prod- 
ucts since practically no middle-men or commission 
merchants will handle it. Another vital question is the 
cost of marketing; if too high, the apparent profits of 
manufacture may be required to meet this cost and again 
the business is a failure. 

186. Demand for ice-cream. — The growing demand 
for ice-cream is indicated by the figures in Chapter XVII. 
The question might naturally be asked why this demand 
is increasing. There are three possible answers to this. 
The consumer in the past regarded ice-cream as a delicacy 
to be indulged in only on special occasions. Now the 
food value is recognized and it is being consumed in large 
quantities as a food. 

In the past it was often difficult to secure ice-cream in 
a satisfactory condition. This was due to a poor delivery 
system and a lack of knowledge regarding the handling. 
At present, however, these difficulties have been over- 
come largely. 

In the hot summer weather, persons like to eat or drink 
some substance which is pleasing to the taste and at the 
same time has a cooling effect on the body; and no dish 
can replace ice-cream for this purpose. 

This condition, namely, the demand for ice-cream in 

246 



MARKETING AND BUSINESS MANAGEMENT 247 

summer and the lack of it in winter, is a matter of great 
concern to the manufacturer. It gives him an unequal 
distribution of his business throughout the year. This 
is a decided disadvantage for several reasons: 1. It is 
hard to secure satisfactory help for a short period of 
time; 2. It is difficult to obtain milk products in sufficient 
quantities only for the hot weather; 3. It requires a large 
investment in equipment which is used only a part of the 
year. The usual result is that the ice-cream manufac- 
turer is forced to pay a higher price for his milk products, 
if he takes them only during the summer. On the other 
hand, if the milk products are purchased by the year, a 
profit is realized during the period of large demand and 
the balance of the year they are handled in some other 
way with a view of breaking even or reducing the loss as 
much as possible. In order to be sure of help for the 
rush season, it is usually necessary to keep at least a part 
of the necessary summer force during the slack season. 
They can be employed in cleaning the plant and making 
the necessary repairs for the next rush season. The 
creating of a market for ice-cream in the winter is an 
unsolved problem. It has been overcome partially in 
some plants by making fancy or special ice-creams. They 
usually require more labor and hence sell at a higher 
price and are in demand for various society functions 
which are more common in the winter. 

187. Food value of ice-cream. — Up to the present 
no investigations have been made dealing with the food 
value or healthfulness of ice-cream. It would seem that 
the previous statements about the food value of milk, 
cream, and butter would apply to ice-cream. Miss Rose * 

* Rose, Flora, "Milk a cheap food," Cornell Reading Course, 
Lesson III, 1917. 



248 THE BOOK OF ICE-CREAM 

gives the following summary regarding the value of milk 
as a food: 

''With all the evidence in, no food bears the investiga- 
tion of nutritive properties better than does milk. It is 
impossible to escape the conviction that not only is it a 
cheap food, but it is one whose value can hardly be esti- 
mated in terms of dollars and cents. It has been pointed 
out that: 

1. Although milk is not the cheapest source of energy 
that can be bought, it is nevertheless an important source 
of energy, and the energy-yielding substances, the pro- 
tein, the milk-sugar, and the milk-fat, have special value. 

2. Milk is a cheap source of protein because the pro- 
tein that it contains is of a kind particularly valuable for 
building tissue. 

3. Ordinarily milk is the cheapest and most valuable 
source of lime, unless it is discovered that lime in water 
can take the place of lime in milk. 

4. Milk is a valuable and cheap source of phosphorus. 

5. Milk is deficient in iron, but the iron that it contains 
is particularly well utilized by the body. 

6. Milk is the most important of the three foods, 
milk, eggs, and meat, which are the chief sources of a 
factor in foods that is soluble in fat, that is essential to 
growth and health, and that is called "fat-soluble A." 

7. Milk is one of the most important sources of a 
factor in foods that is soluble in water, that is essential 
to growth and health, and that is called "water-soluble 
B." 

Jerome Alexander * shows the effect of gelatine on the 

* Alexander, Jerome, ''The beneficial effect of gelatine upon the 
digestion of milk and cream," "Ice-cream Trade Journal," Vol. 5, 
No. 2. . 



MARKETING AND BUSINESS MANAGEMENT 249 

digestibility of milk products. The chief constituents 
of ice-cream are crystalloids; that is, substances that can 
form crystals, whereas gelatine is a most characteristic 
member of the group of non-crystallizing substances 
known as colloids. Research has shown that colloids or 
hydrosols as they are sometimes known may be divided 
into two classes or groups; depending on the way they 
behave when they dry out. The first group which in- 
cludes those that can be redissolved after being dried, 
such as gelatine, are called the reversible colloids or 
reversible hydrosols. The second group, which includes 
those that cannot be redissolved after drying, such as 
pure colloidal metals, oxides and the like, are known as 
irreversible colloids or irreversible hydrosols. The re- 
versible colloids are not sensitive but will stand the addi- 
tion of most substances without coagulation. In the case 
of ice-cream, the addition of gelatine tends to prevent the 
coagulation of casein, which is an irreversible colloid and 
the important proteid or nitrogenous constituent of 
cows' milk. For this reason gelatine renders ice-cream 
more readily digestible and therefore more healthful; as 
is well known, milk is immediately coagulated on coming 
in contact with the acid juices of the stomach. But in 
the presence of gelatine the casein is either prevented 
from coagulating or if it does coagulate the clots or curds 
are so fine grained that they dissolve very easily in the 
process of digestion. 

The composition of ice-cream varies with the materials 
used. The flavoring material affects the percentage com- 
position. The following are fair examples of the chemical 
composition of commercial vanilla ice-cream containing 
different percentages of fat: 



250 THE BOOK OF ICE-CREAM 







Table XIV 






Composition of Ice- 


cream Containing Different Percentage 


5 of Fat 


Sample 






Carbo- 






Number 


Fat 


Protein 


hydrates 


Water 


Ash 


1 


.. 8.5.. 


....3.0... 


...22.50... 


...65.0..... 


.1.0 


2 


..14.0.. 


....2.2... 


...20.00... 


...63.0 


.0.8 


3 


.. 8.0. . 


....4.0... 


...21.10... 


...66.0 


.0.9 



Ice-cream is often considered a possible source of pto- 
maine poison and typhoid fever. If not properly handled 
and allowed to melt and then returned and refrozen or 
made from poor materials, there may be danger of disease. 
But under the sanitary condition of most of the plants, 
especially the large ones, there is no more danger from 
ice-cream poisoning than from any other class of food. 

188. Locating a market'. — Believing that there is a 
general demand for ice-cream, the question naturally 
follows where is the most desirable location or market. 
Because of the large number of consumers, the city natu- 
rally^ offers the best market. If a large plant is planned, 
the usual system is to wholesale the ice-cream to the 
retailer. If a smaller plant is desired, the market may 
be a retail business only; in this case it may be a hotel, 
drug-store, soda fountain or summer resort. Several 
creameries are located on trunk lines of improved roads 
and make ice-cream as a side line, catering entirely to 
automobile parties. 

189. Method of delivery. — For the retailer the ques- 
tion of delivery is very simple, but for the wholesaler it is 
a very perplexing problem. • There are three ways by 
which the wholesaler may make delivery: by express, 
automobile truck, wagons and horses. 

If the plant is in a large city, the ice-cream may be 
shipped by express to retailers in the surrounding small 



MARKETING AND BUSINESS MANAGEMENT 251 

towns. The distance that shipments can be made by 
express depends on the facilities of the railroad. If on 
a main line with fast trains, shipments may be sent 300- 
500 miles. Ice-cream should not be shipped so far that 
it will soften before it reaches the retailer. 

In the city, the manufacturer must decide which is the 
more economical, to use horses and wagons or automobiles. 
Each has its advantages and disadvantages, some of which 
are as follows : 

Advantage of automobile truck: 

1. Can make quicker delivery than horses and wagon. 

2. Can carry larger load. 

Disadvantage of automobile truck: 

1. Large initial cost. 

2. Requires higher salaried person to operate it than 
to drive horses. 

3. Cannot be used year round in some snowy localities. 

4. Engine may be left running while making delivery. 
This is expensive. 

5. Large loss in case of accident. 

Advantage of horses and wagons: 

1. Can be used year around. ■ 

2. Easy to get person to drive horses. 

3. Not as expensive as large truck to purchase. 

Disadvantages of horses and wagons: 

1. Slower than automobile truck. 

2. Liable to tire out in hot weather. 



252 



THE BOOK OF ICE-CREAM 



190. Cost of delivery. — This is so variable that even 
average figures would be misleading. The cost of delivery 
should be based both on the cost a gallon and the cost a 
load. These figures should be watched and a reason found 
for a marked increase. Otherwise, the cost of delivery 
may grow so that it will consume all profits. One of the 
large items is the ice necessary to pack the ice-cream in 
the retailer's cabinets. 

191. Packages used for delivery. — When drawn from 
the freezer, the ice-cream is placed in pack-cans or brick 

molds. When delivery is 
made to the retailer, the ice- 
cream is usually left in the 
pack-can. For delivery by 
express or to the individual 
consumer, the can is packed 
in a tub with ice and salt. 
The size of the tub varies 
with that of the pack-can. 
(Fig. 77.) The small tubs 
usually have bails and the 
large tubs handles on the side. 
For city delivery of wholesale ice-cream, the wagon or auto 
truck (Fig. 78) is equipped with a cabinet and the cans 
packed in these cabinets. This eliminates the heavy tubs. 
Ice and salt are carried for packing the ice-cream in the 
retailer's cabinet. Most manufacturers furnish the retailer 
with a cabinet (Fig. 79) in which the ice-cream is packed 
until retailed. These cabinets are usually insulated. 
They are made in various sizes to hold one or several pack- 
cans of ice-cream. In the cabinet is usually a form which 
fits around each can so that it may be removed and an- 
other full one put in without the ice caving in. This 




Fig. 77. 



-Ice-cream packing 
tubs. 



MARKETING AND BUSINESS MANAGEMENT 253 

form has numerous holes in it so that the cold air and 
brine can get to the pack-can. The cabinet is fitted with 
a large cover in which are smaller openings and covers 
for each can. These smaller openings are used when dip- 
ping the ice-cream. 

Before delivery to the consumer or the retailer, the brick 
ice-cream is usually taken from the mold and wrapped 




Fig. 78. — Auto delivery truck for ice-cream. 

in paper. This eliminates the return of the metal form. 
These bricks may then be packed in ice and salt or simply 
wrapped in additional paper, depending on how long the 
ice-cream must be kept before it is to be consumed. Sev- 
eral paper carriers have been devised, but they are not in 
general use. 

The retailer makes his deliveries directly to the con- 
sumer, either to be eaten immediately or carried home. 



254 



THE BOOK OF ICE-CREAM 



When delivery is made to be consumed immediately, 
the ice-cream is dished with a measuring disher and placed 
in an individual dish. There are a large number of styles 
of these dishers. (Fig. 80.) Each has some sort of a knife 
or scraper to remove the ice-cream from the disher. The 

size is expressed in 
the number that it 
takes to make a quart. 
The disher is used as 
the measure whether 
the ice-cream is sold 
by the dish, in the 
soda glass or cone. 
A large amount is sold 
in the latter. There 
is no objection to the 
cone itself if it is 
made of pure harm- 
less materials. It is 
Fig. 79. — Ice-cream cabinet with sides often sold from push 
cut away showing insulation and ^^^^^ ^^^ venders' 
perforated cyhnders in which the 
pack-cans of ice-cream set. wagons, where there 

is great opportunity 
for dirt to get into the ice-cream both before and after 
it reaches the consumers' hands. 

Another device through which a large amount of 
ice-cream is sold is the ice-cream sandwich machine. 
This places a slice of brick ice-cream between two 
wafers. 

When the ice-cream is sold by the retailer to the con- 
sumer to be carried away and consumed later, it is packed 
in a heavy manilla paper pail. These vary in size from 
a pint to two quarts. If the ice-cream is hard and the 




MARKETING AND BUSINESS MANAGEMENT 255 

pail wrapped in paper, it may be held for an hour or more 
before it begins to melt. 

While the ice-cream may be made of high grade mate- 
rials and under the most sanitary conditions, many of the 
places where it is retailed are not clean. The single- 
service paper plate and spoon are to be desired in prefer- 




FiG. 80. — Different styles of ice-cream dishers. 

ence to the dish and silver-plated spoon which is rinsed 
off in cold water. It is to the advantage of the manu- 
facturer to see that the places where his ice-cream is sold 
are kept in a clean sanitary condition. 

192. Advertising. — The manufacturer must keep the 
attention of the pubhc centered on his ice-cream. This 
can be done only by advertising. There are several ways, 
but the best is to let the product advertise itself. If an 



256 THE BOOK OF ICE-CREAM 

ice-cream appeals to the desires of the consumer and is 
uniform, it will be in demand. 

The newspapers may be employed also as an advertis- 
ing medium. In some localities the advertisement has 
appeared for so long in some particular space in the paper 
that the consumer has become accustomed to look there 
to learn what special ice-creams will be made for holidays 
and Sundays. 

The paid reading advertisement in the newspaper is a 
form conamonly used. This differs from the ordinary 
form in being printed the same as any news item. It 
should not be too long and should be concise and clear 
to the reader. 

The society columns should be watched and an effort 
made to sell one's ice-cream at any large gathering. This 
is especially true of church functions. The person in 
charge may be communicated with either by telephone 
or a neat attractive letter. Extra effort should be made 
to have the ice-cream of good quality. It may not be 
profitable to furnish ice-cream at these functions, but if the 
advertising feature is considered it will be very valuable. 

The bill-board is another means of advertising and is 
very effective in impressing the name of the ice-cream on 
the public. It is usually expensive. 

The results of advertising are ordinarily hard to 
measure exactly, but it is a necessary part of the business. 
The value of advertising in the winter, when there is not 
a large demand for ice-cream and many specialties have 
to be manufactured, should not be overlooked. There 
are many schemes for advertising, and which will be tried 
and which rejected will have to be determined by the 
manufacturer. The underlying principle is the same in 
all. They should be attractive; they should state some 



MARKETING AND BUSINESS MANAGEMENT 257 

fact about the ice-cream; the wording should be such as 
to induce the reader to try a dish. The value of adver- 
tising is especially difficult for a beginner to see. The 
amount of money that can or should be used for adver- 
tising will have to be determined by several facts, such 
as number of local newspapers, number of towns where 
ice-cream is sold, amount of education necessary to create 
a demand. 

Under no circumstances, in any advertisement or in 
any other way, should a manufacturer run down the qual- 
ity of his competitors' products. 

It is often desirable to have some short attractive 
expression to use with the advertisement. 

193. Salesmen.— In the large plants, salesmen are 
necessary to call on the trade to sell, the ice-cream and 
adjust any differences that may arise. The kind of sales- 
man has much to do with the success of the business. 
He should be neat and clean in appearance; he must have 
the faculty of getting along with people; he must have 
good business ability and be able to make sales. It is 
not the first sale that counts but the repeated orders that 
are necessary to put the business on a firm foundation. 

BUSINESS MANAGEMENT 

The success of a plant is not alone in being able to make 
ice-cream of good quality, although this may be the major 
item. The business management is very important. 
This consists of the buying, handling the workmen, mak- 
ing the sales and in general keeping track of the financial 
end of the plant. In many cases it is necessary to check 
up the losses. 

194. Purchase of raw material. — All raw materials used 
in the ice-cream should be purchased on the basis of their 



258 THE BOOR OF ICE-CREAM 

composition rather than by quantity. For example, it is 
very poor business to buy milk and cream for a certain 
price a quart or gallon regardless of the percentage of fat 
contained. The percentage of fat in the milk is largely 
influenced by the season of the year and the lactation 
period. Even more variable is the percentage of fat in 
the cream, the fat-content varying from the same creamery 
or same separator. Some of the causes of variation in 
the test of cream are: 1. Adjustment of the cream screw; 
2. Richness of milk separated; 3. Amount of material used 
to flush the bowl; 4. Speed of the separator; 5. Tempera- 
ture of milk when separated; 6. Rate of flow of the milk 
to the machine. 

The composition of the other materials will vary the 
same as does the milk and cream. Each shipment should 
be tested to make sure that it is of the proper composition. 
This may take some time, but it pays in the end. 

195. Price of dairy products. — There is no market 
quotation for any except the manufactured dairy prod- 
ucts such as butter and cheese. Ordinarily the price of 
milk and cream follows that of these manufactured prod- 
ucts very closely. The price of butter and cheese are 
quoted daily in New York City in the "Price Current" 
published by the Urner Barry Company. From this the 
price of milk and cream can be estimated. In some cases, 
the price of the fat in the cream is based on the price of 
butter. 

196. Book-keeping system. — A simple yet complete 
set of books should be kept. A cost system seems best 
adapted and the most simple. 

To obtain a cost system it is very essential that every 
penny should be accounted for and charged to the account 
for which the expenditure was made. The numerous 



MARKETING AND BUSINESS MANAGEMENT 259 

accounts that will have to be maintained in order to keep 
this system should be classified under the headings of 
production costs and sales costs. In opening the accounts 
for production cost, it is necessary that the following 
heads should be carried: 

1. Milk, cream, butter. Express should be added to the cost 
of the above where any of the same is shipped. 

2. Labor. Salaries for ice-cream maker, mixers, and helper. 
The remaining help throughout the plant is carried under a 
different heading which does not apply specifically to the pro- 
duction department. 

3. Supplies used. This account should be carried under 
several different headings, as: 

(a) Sugar 

(b) Milk powder 

(c) Gelatin3 

(d) Gum 

(e) Fruits 

(f) Extracts 

(g) Miscellaneous 

4. Ice and salt (when ice and salt are used for the freezing of 
the cream). But in case mechanical refrigeration is employed 
for freezing and ice and salt for hardening, it should be charged 
to the production cost; otherwise it should be figured into the 
sales cost just the same as delivery or other expense. 

5. Water and steam. 

6. Sundry expense. 

By keeping these accounts monthly, the production 
cost for every month is computed for the year. 
Sales cost should include: 



1. 


Rent. 


2. 


Salaries. 




(a) Executive. 




(b) Office. 




(c) Salesmen. 




(d) Delivery drivers. 




(e) Labor. (Can-washers 




employed.) . 



and such other help as is 



260 THE BOOK OF ICE-CREAM 

3. Advertising. 

4. Ice (as used in packing for deliveries). 

5. Miscellaneous expenses. 

6. Taxes. 

7. Insurance. 

8. Bad debts. 

9. Postage and stamps. 

10. Trucks, or horse and wagon expense. 

11. Traveling expense. 

12. Telephone and telegraphic expenses. 

13. Salt. 

14. Depreciation. 

15. Repairs and replacements. 

16. Stationery. 

17. Shrinkage. 

18. Such other items of sales cost as you may see fit to carry 
under separate headings. 

Taking the number of gallons sold, it is an easy matter 
to divide this into any one of the numerous accounts 
under either the head of production or sales cost, which 
will give the cost a gallon of this account and place the 
manager in a position to keep in touch with every account 
as to the actual cost a gallon each month. By making 
comparisons month after month, it will be easy to de- 
termine wherein the costs are excessive. 

197. Shipping clerk. — ^No ice-cream business is too 
small or too large to have a shipping clerk. In a small 
plant, the shipping may not require all one man's time 
so that he may have other duties. The shipping platform 
and office of the shipping clerk in a large ice-cream plant 
is shown in Fig, 81. It is the duty of the shipping clerk 
to see that the orders are properly put up and that they 
are delivered on time. He must check the ice-cream to 
the drivers and see that each has the correct amount of 
salt and ice. It is sometimes the custom of the drivers 
to take extra ice and salt and sell it on the side. He must 



MARKETING AND BUSINESS MANAGEMENT 261 

also check back any ice-cream returned by the drivers. 
The position of shipping clerk is one of the most im- 
portant in the whole' business management. 

198. Report blanks. — Every person who has charge 
of any part of the ice-cream business should make a 
report. By means of these daily reports, any leaks or 
losses may be checked up. It also makes easy the keep- 
ing track of the business. Forms for these reports are 




Fig. 81. — Shipping platform and office of shipping clerk in a large 

ice-cream plant. 

not included because the demand in each plant would 
probably be different. The receiving-room report should 
show the amount of milk and milk products received and 
the percentage of fat in each and the total receipts. The 
mixing-room report should indicate the amount of ma- 
terials used. The freezing-room report should show the 
number of freezers of ice-cream made, the swell obtained 
in each and the total gallons. The shipping-room report 
should tell the number of gallons shipped out. The 
drivers' report should show the amount of ice-cream 
received, the amount returned and the amount sold, to 



262 THE BOOK OF ICE-CREAM 

whom sold, whether cash or credit, and thq cash and 
credit should equal the amount sold. These reports may 
be combined more or less, depending on the size of the 
plant. A loose-leaf or card system for filing in many 
cases would reduce the office work. 

199. Losses. — In any business there are more or less 
losses. These are usually inversely in proportion to the 
efficiency of the business management. In ice-cream 
marketing, certain leaks or losses are liable to occur and 
these should receive special mention. 

200. Pack-cans and tubs. — Undoubtedly there is no 
part of the business that causes the manager more anxiety 
than the return of the empty pack-cans and tubs. This 
is especially true when a considerable part of the ice- 
cream is shipped by express. Many schenies have been 
tried to return these tubs, such as paying the drivers a 
percentage for the return of a certain number, charging 
the person to whom the ice-cream was sold for the can 
and tub, hiring a special man to look up the can and tub, 
and many others. The one commonly used by manufac- 
turers is to have a distinctive color on the tub, their name 
and address and also a number. The shipping tags are 
made with a stub that is perforated so that it can be 
detached easily. When the tag is attached to the tub, 
the number is placed on both the tag and the stub. The 
stub should contain date and name and address of the 
party to whom shipped. It is often desirable to have the 
gallons and kind of ice-cream shipped on both the stub 
and the tag. This stub is filed in the office and when the 
tub is returned the tag is taken off and sent in and the 
stub bearing the same tub number put with it, indicating 
that tub has been returned. By looking at the stubs for 
which the corresponding tags have not been returned, it can 



MARKETING AND BUSINESS MANAGEMENT 263 



be seen readily to whom, where, and when the tubs were 
shipped and what parties are not returning the empties. 

201. Rusty pack-cans. — Because of the salt that must 
be used to harden the ice-cream, more or less gets on to 
the pack-cans and rusts them, especially if they are not 
washed as soon as emptied. These rusty cans may be 
retinned. Another satisfactory plan is to line the can 
with heavy manilla paper. These liners may be purchased 
to fit any size pack-can. 

202. Soft ice-cream. — Often the top of the can of ice- 
cream will become soft, due to the lack of salt and ice 
on top. Sufficient may have been put on but it jarred 
off while handling. This loss can be avoided by t3dng 
a piece of heavy paper or burlap over the top of the can. 
Heavy canvas covers may be purchased. 

Sometimes a large amount of refrigeration is lost by 
putting the ice-cream into the hardening-room through 
the large door where 
persons pass in and 
out. A small revolv- 
ing door (Fig. 82) 
will reduce this loss. 
There is a very rapid 
change of air when 
the hardening-room 
door is opened. The 
greater the differ- 
ence in temperature, 
the more rapid the change. Soft ice-cream soon ruins 
the reputation of the business. 

203. Transferring. — ^When drawn from the freezer, the 
ice-cream should be put into the size pack-can in which 
it will be delivered to the consumer or retailer. If it is 




Fig. 82. — Revolving door used for putting 
the ice-cream into the hardening- 
room. 



264 THE BOOK OF ICE-CREAM 

necessary to transfer from one can to another, there is a 
big loss in volume. This loss is probably caused by squeez- 
ing the ice-cream into the other container, which closes 
the air spaces. 

When the ice-cream is handled in the retail store, a loss 
may be caused by the heaping up of the dishes. Several 
scrapers or levelers have been devised to insure a uniform 
sized dish. If the dishers are kept in hot water, they will 
work much better in hard ice-cream. Some sort of scraper, 
of which there are several on the market, should be used 
to scrape the ice-cream from the sides of the can. 

LAWS 

Several laws apply to ice-cream. Some of these refer 
to the production of the milk and the balance are stand- 
ard of quality based on chemical composition or stand- 
ards for materials used. 

204. Sanitary conditions and adulterated milk and 
cream. — ^Most of the states have laws dealing with the 
sanitary conditions under which milk and cream may be 
produced. The following law * of Wisconsin is a good 
example : 

''Adulterated milk, what constitutes. Section 4607a. 
In all prosecutions under the preceding section, or any 
other section of these statutes, or laws amendatory thereof 
or supplementary thereto, relating to the sale of adulter- 
ated milk or adulterated cream, the term adulterated 
milk shall mean: Milk containing less than three per 
centum of milk fat, or milk containing less than eight and 
one-half per centum of milk solids not fat, or milk drawn 
from cows within eight days before or four days after 
parturition, or milk from which any part of the cream has 
* Dairy Laws of Wisconsin 1916, section 4607a. 



MARKETING AND BUSINESS MANAGEMENT 265 

been removed, or milk which has been diluted with water 
or any other fluid, or milk to which has been added or 
into which has been introduced any coloring matter or 
chemical or preservative or deleterious or filthy substance 
or any foreign substance whatsoever, or milk drawn from 
cows kept in a filthy or unhealthy condition, or milk drawn 
from any sick or diseased cow or cow having ulcers or 
other running sores, or milk drawn from cows fed unwhole- 
some food, or milk in any stage of putrefaction, or rnilk 
contaminated by being kept in stables containing cattle 
or other animals. The term adulterated cream shall 
mean containing less than eighteen per centum of milk 
fat, or cream taken from milk drawn from cows within 
eight days before or four days after parturition, or cream 
from milk to which has been added or introduced any 
coloring matter or chemical or preservative or deleterious 
or filthy substance or any foreign substance whatsoever, 
or cream from milk drawn from cows kept in a filthy or 
unhealthy condition, or cream from milk drawn from any 
sick or diseased cow or cow having ulcers or other running 
sores, or cream from milk drawn from cows fed unwhole- 
some food, or cream contaminated by being kept in stable 
containing cattle or other animals, or cream to which has 
been added or into which has been introduced any color- 
ing matter or chemical or preservative or deleterious or 
filthy substance or any foreign substance whatsoever, or 
cream in any stage of putrefaction; provided, that nothing 
in this act shall be construed to prohibit the sale of pas- 
teurized milk or cream to which viscogen or sucrate of 
lime has been added solely for the purpose of restoring 
the viscosity, if the same be distinctly labeled in such man- 
ner as to advise the purchaser of its true character; and 
providing that nothing in this act shall be construed as 



266 THE BOOK OF ICE-CREAM 

prohibiting the sale of milk commonly known as ' skimmed 
milk,' when the same is sold as and for 'skimmed milk.' 
Milk drawn from cows within eight days before or four 
days after parturition, or milk to which has been added 
or into which has been introduced any coloring matter 
or chemical or preservative or deleterious or filthy sub- 
stance, or milk drawn from cows kept in a filthy or un- 
clean condition, or milk drawn from any sick or diseased 
cow or cow having ulcers or other running sores, or milk 
drawn from cows fed unwholesome food, or milk contam- 
inated by being kept in stables containing cattle or other 
animals and cream from any such milk, or cream in any 
stage of putrefaction are hereby declared to be unclean 
and unsanitary milk or unclean and unsanitary cream, 
as the case may be." 

Most of the states have laws which determine the legal 
standard of milk. Anyone selling milk which does not 
meet the legal standard is liable to be fined. The laws of 
most states prohibit the taking of anything from or the 
adding of anything to the milk. This prohibits skimming 
and watering. Skim-milk must be sold as such. 

205. Babcock test. — Some states have laws specifying 
that all glassware used in the Babcock test shall be stand- 
ardized. Standard glassware shall bear a certain brand 
to indentify it. This brand is placed on it after being 
tested by the proper state official. Some of the states 
have laws requiring the operator of the Babcock test to 
procure a license. 

206. Purchasers or vender's license. — In some states a 
concern to purchase milk or cream from the producer must 
have a license. This is to prevent parties not financially 
responsible from buying milk and later beating the pro- 
ducer. The license is given only on the filing of a bond. 



MARKETING AND BUSINESS MANAGEMENT 267 

In some cities ice-cream cannot be sold without a 
license. This is for the purpose of controlling sanitary 
conditions. 

207. Legal standards. — Most states have legal stand- 
ards for dairy products. The standard for the different 
states is given in Table * XV. 

U. S. DEPARTMENT OF AGRICULTURE 
BUREAU OF ANIMAL INDUSTRY 

A. D. MELviN, Chief of Bureau 

LEGAL STANDARDS FOR DAIRY PRODUCTS 

{Revised to July 1, 1915) 

In the following statement, prepared in the Dairy Division of 
the Bureau of Animal Industry, are given the standards for dairy 
products as established in the several states, including Alaska, 
the District of Columbia, Hawaii, the Philippines, and Porto 
Rico. In all cases, unless otherwise expressed, the percentages 
stated represent minimum standards. 

The department publishes these figures as given by various 
state authorities, but does not guarantee the correctness of the 
standards given. 

* Melvin, A. D., "Legal standards for dairy products," A8, 1916. 



268 THE BOOK OF ICE-CREAM 

Table XV. — Legal Standards for Dairy Products. 



States 


Milk 


Skim 

MILK 


Cream 


Butter 


Total 
solids 


Solids 
not fat 


Fat 


Total 
solids 


Fat 


Fat 


Water 


Salt 


Alabama ^ 


Per ct. 


Per ct. 


Per ct. 


Per ct. 


Per ct. 


Per ct. 


Per ct. 


Per ct. 


Alaska 2 


















ArizoDa ' 


















Arkansas ^ 


















California 




8.50 


3.00 
3.00 
3.25 


8.80 


18.0 
16.0 
16.0 


80.0 
80.0 






Colorado 




16.00 

(0 




Connecticut 


11.75 


8.50 


(■) ^ 


Delaware 1 


District of Columbia. . 
Florida 


12.50 


9.00 
8 . 50 
8.50 

's^oo' 

8.50 
8.50 


3.50 
3.25 
3.25 
2.50 
3.20 
3.00 
3.25 
3.00 


9.30 
9 . 25 
9.25 

'9!3()' 
9 . 25 
9.25 


20.0 
18.0 
18.0 
18.0 
18.0 
18.0 
18.0 
16.0 
18.0 
18.0 

(') 
18.0 
18.0 
15.0 
18.0 
20.0 


83.0 
82.5 
82.5 


12.00 


5.00 


Georgia . 




16.00 




Hawaii 


11.50 
11.20 




Idaho 


82.5 
82.5 
82.5 
80.0 
80.0 
82.5 
V) 


16.00 




Illinois 




Indiana 




16.00 




Iowa 


12.00 




Kansas 


3.25 
3.25 
3.50 
3.25 
3.50 
3.35 
3.00 
3.25 


"9;25' 
8.00 

"9;25' 
"9.30 


ie.oo 




Kentucky 




8.50 
8.50 
8.50 

'9!75' 




Louisiana 




C) 


(') 


Maine 


11.75 
12.50 
12.15 
12.50 
13.00 


Maryland 








Massachusetts 








Michigan 


80.0 






Minnesota 


16.00 




Mississippi ^ 




Missouri 


12.00 
11.75 


.8.75 
8.50 


3.25 
3 . 25 
3.00 


9.25 

's.ho' 

9.25 


18.0 
20.0 
18.0 
18.0 
16.0 


82.5 
82.5 






Montana 


16.00 




Nebraska 




New Hampshire 


12.00 
11.50 




80.0 
82.5 


16.00 




New Jersey 




3.00 




New Mexico ' 






Nevada 

New York 


11.75 
11.50 
11.75 
12.00 
12.00 


8.50 

k'.ho 


3.25 
3.00 
3.25 
3.00 
3.00 


9.25 
'9!25' 


18.0 
18.0 
18.0 
15.0 


82.5 


16.00 




North Carolina 


82.5 






North Dakota 

Ohio 


V) 


C) 


Oklahoma '^ 












Oregon 


11.70 
12.00 
11.75 


8.50 
'8.56' 


3.20 
3.25 
3.25 


9.25 


18.0 
18.0 
18.0 


80.0 
82.5 


16.00 

0) 




Pennsylvania 

Philippine Islands. . . . 


V) 


Porto Rico 15 






Rhode Island 


12.00 




2.50 






82.5 






South Carolina 1 










South Dakota 




8.50 
8.50 
8.50 
8.80 
8.50 
8.50 
8.75 


3.25 
3.50 
3.25 
3.20 
3.25 
3.25 
3.25 


9.25 
9.00 
9.25 

'9;25' 
9.25 
9.30 


18.0 
20.0 
18.0 
18.0 
18.0 
18.0 
18.0 


80.0 
82.5 
82.5 
80.0 
82.5 
82.5 






Tennessee 


12.00 
12.00 
12.00 
11.75 


15.99 




Texas 




Utah 

Vermont 


16.00 




Virginia 


16.00 




Washington 


12.00 




West Virginia 1 








Wisconsin. . ."". 




8.50 


3.00 


9.00 


18.0 


82.5 






Wyoming ' 








United States 




8.50 


3.25 


9 25 


18.0 


82.5 


2716.00 













See notes on page 269. 



MARKETING AND BUSINESS MANAGEMENT 269 

1 No state standards. 

2 No territorial standards. 

3 Federal standards for all food products. Fillers in ice-cream may be used if 
large label is displayed in all places of sale. 

^ Percentage of fat based on total solids. 

5 Must be labeled. 

6 Classed as condensed. 

7 United States standard. 

8 United States food and drugs act of 1906 applies to the District of Columbia. 

9 Should be labeled. 

10 Not allowed. 

11 Must be so branded. 

12 Defined, but no standard. 

13 Any amount if fat is maintained. 
» Solids in fat. 

15 Must correspond on stated dilution to state standards for milk. 

16 Any less than 30. 

17 All below 45. 

18 Less than 13 marked skim; 13 to 18, medium skim; 18 or over special skim. 

19 Must correspond to 11.5 per cent solids in crude milk; one-foarth to be fat. 

20 Two ounces in 10 gallons if labeled gelatine ice-cream. 

21 Full cream, 30. Standard, 21. 

22 Must correspond to 12 per cent of solids in crude milk; one-fourth to be fat. 

23 Less than 7.5, skim; 7.5 to 15, three-fourths skim; 15 to 30, half skim. 

2* Three-fourths cream, 24; one-half cream, 16; one-fourth cream, 8. Skim, less 
than 8. 

25 Less than 30. 

26 Less than 30; less than 15 not allowed. 

27 Less than 16. This applies to all butter made in United States territory. 

No reports gave standards for powdered milk. 



270 



THE BOOK OF ICE-CREAM 



Table XV — Legal Standards for Dairy Products — Continued. 



States 



Condensed 

MILK 

(sweetened) 



Alabama i 

Alaska 2 

Arizona ' 

Arkansas i 

California . . . 

Colorado 

Connecticut 

Delaware ' 

District of Columbia. 

Florida 

Georgia 

Hawaii 

Idaho 

Illinois 

Indiana 

Iowa 

Kansas 

Kentucky 

Louisiana 

Maine 

Maryland 

Massachusetts 

Michigan 

Minnesota 

Mississippi ^ 

Missouri 

Montana 

Nebraska 

New Hampshire. . . . 

New Jersey 

New Mexico i 

Nevada 

New York 

North Carolina 

North Dakota 

Ohio 

Oklahoma i^ 

Oregon 

Pennsylvania 

Philippine Islands. . . 

Porto Rico IS 

Rhode Island 

South Carolina ^ . . . . 

South Dakota 

Tennessee 

Texas 

Utah 

Vermont 

Virginia 

Washington 

West Virginia ^ 

Wisconsin 

Wyoming ^ 

United States 



Total 
solids 



Per ct. 



Fat 



Per ct. 



EVAPORATED 

MILK (un- 
sweetened) 



Total 
solids 



Per ct. 



Fat 



Per ct. 



Ice cream 

(plain) 



Fat 



Per ct. 



Gela- 
tine 



Per ct. 



Ice cream 
(fruit and 

nut) 



Fat 



Per ct. 



Gela- 
tine 



Per ct. 



24.5 
28.0 
28.0 



7.70 

7.70 

43L00 



25.5 

C) 

(«) 



7.80 

(«) 

(«) 



10.0 
14.0 



0.6 



8.0 
12.0 



28.0 

(0 



(«) 

7.70 



(«) 
24.0 



(«) 

7.80 



12.0 
12.0 



(«) 



10.0 



28.0 
28.0 
34.3 

(') 



427.60 
7.70 
7.80 
V) 



25.5 
25.5 



7.70 
7.80 



28.0 

(J) 
26 . 5 
34 . 3 

(...) 

28.0 



427.66 

0) 
429.50 

7.80 

(.5) 

8.00 



28.0 

C) 
26.5 



427.66 
429.50 



C) 
25.5 



(0 
7.80 



14.0 

8.0 

8.0 

12.0 

14.0 

14.0 

10.0 

14.0 

4.0 

7.0 

10.0 

12.0 



(.0) 



.7 
1.0 



1.0 

(13) 



.7 



12.0 

8.0 

8.0 

10.0 

12.0 

12.0 

8.0 

12.0 

6.0 

7.0 

8.0 

12.0 



28.0 



427.67 



28.0 



427.67 



Q) 



Q) 



(.') 



(') 



14.0 
12.0 
14.0 
14.0 



1.0 



12.0 
10.0 
12.0 
14.0 



28.0 

(19) 

25.5 

(22) 



427.50 

(19) 

7.80 
(0 

(22) 



25.5 



7.80 



14.0 



12.0 



25.5 



7.80 



10.0 
14.0 



(20) 



8.0 
12.0 



28.0 



C) 
427.50 



32.3 

(J) 
25.5 



7.80 
7.80 



12.0 

8.0 

14.0 



1.0 

.5 



9.0 

6.0 

12.0 



25.0 



7.80 



25.0 



7.80 



8.0 



1.0 



8.0 



28.0 
25.5 

C) 

{') 

28.0 
28.0 



427.50 

7.80 

C) 

U) 

427.50 

427.50 



28.0 
25.5 

C) 

V) 
34.3 
28.0 



427.50 
7.80 
(1 

7.80 
427.50 



14.0 

8.0 . 

8.0 

14.0 
8.0 



■(2i)' 



12.0 
.7.0 

6.0 

(') 
12.0 

8.0 



28.0 
28!6 



8.00 
'427.56 



28.0 



8.00 



14.0 



25.5 



7.! 



14.0 



12.0 
12.6. 



See notes on page 271. 



0.6 



(») 



(.0) 



.7 
1.0 



1.0 

(13) 



.7 



1.0 



.2 



(20) 



1.0 
.5 



1.0 



■(23)' 



MARKETING AND BUSINESS MANAGEMENT 271 

I No state standards. 

" No territorial standards. 

^ Federal standards for all food products. Fillers in ice-cream may be used if 
large label is displayed in all places of sale. 
* Percentage of fat based on total solids. 
5 Must be labeled, 
fi Classed as condensed. 
^ United States standard. 

8 United States food and drugs act of 1906 applies to the District of Columbia. 

9 Should be labeled. 

10 Not allowed. 

II Must be so branded. 

12 Defined, but no standard. 

13 Any amount if fat is maintained. 

14 Solids in fat. 

15 Must correspond on stated dilution to state standards for milk. 

16 Any less than 30. 
" All below 45. 

18 Less than 13 marked skim; 13 to 18, medium skim; 18 or over, special skim. 

19 Must correspond to 11.5 per cent solids in crude milk; one-fourth to be fat. 

20 Two ounces in 10 gallons if labeled gelatine ice-cream. 

21 Full cream, 30. Standard, 21. 

22 Must correspond to 12 per cent of solids in crude milk; one-fourth to be fat. 

23 Less than 7.5, skim; 7.5 to 15, three-fourths skim; 15 to 30, half skim. 

24 Three-fourths cream, 24; one-half cream, 16; one-fourth cream, 8. Skim, less 
than 8. 

25 Less than 30. 

26 Less than 30; less than 15 not allowed. 

27 Less than 16. This applies to all butter made in United States territory. 



CHAPTER XVI 

CONSTRUCTION AND ARRANGEMENT OF THE 

FACTORY 

The exterior construction of the ice-cream plant is of 
little importance as long as the building is large and strong 
enough to hold the business, and is neat and clean. The 
building may be of brick, wood, hollow tile, cement block 
or any other satisfactory material. The interior arrange- 
ment should receive careful study and planning. In a 
new building, devoted to the manufacture of ice-cream, 
the details usually can be included in the plans. How- 
ever, it is often necessary to use some building which was 
not especially constructed or arranged for ice-cream- 
making. An old building usually can be rearranged so 
that it will be suitable and fairly convenient. It should 
be large enough to give sufficient room for the machinery 
and space for working. If a new building is being con- 
structed, the plans should be made with a view of possible 
needs for enlargements. The building should not be so 
large that there will be waste space. This causes unnec- 
essary expense and requires useless labor to keep clean. 
Certain considerations should be kept in mind, whether 
building a new plant or rearranging an old building. These 
are discussed in the following paragraphs. 

208. Location of the plant. — For the ease of delivery, 
the plant should be located as near the center of the city 
as possible. If it is planned to ship much ice-cream by 
express, a location near the express company is desirable. 

272 



CONSTRUCTION OF FACTORY 



273 



If it is a small plant and expects to conduct a retail busi- 
ness principally, the location should be on one of the main 
streets of the town in order to reach as many of the con- 
suming public as possible. Usually sewage connections 
can be secured in any part of the city so this factor need 
not be considered. The question of a clean atmosphere 
about the factory is of much importance; if located in a 




DRIVE WAY 
Fig. 83. — Plan of small ice-cream plant. 

manufacturing section of the city, it is almost impossible 
to keep the factory clean because of the smoke and 

cinders. 

209. Arrangement of machinery.— Because of the large 
number of difficult makes of the same kind of machine 
and the variation in size of the different types, it is impos- 
sible to make exact plans without knowing the exact size 
of the machine. In a small plant all the machinery is 
usually located on the same floor. Such an arrangement 
is shown in Fig. 83. This is intended as both a retail and 
wholesale plant. The retail salesroom might be omitted 
and the plans used for a small wholesale plant. A small 



274 



THE BOOK OF ICE-CREAM 



boiler for heating water for washing and sterilizing the 
utensils might be located in the basement. If desired, 
tanks for the making of ice might also be placed in the 
basement. Such a plan is shown in Fig. 84. The arrange- 
ment should be such as to follow the natural sequence of 
the process as far as possible. The second story or attic 
might be used as a storeroom. 



^\vv\mvvvvvvvvvvvvvvv\vvv\vvvvvvvvvvv^^^^^ 



i^'.^'-kk^kk'.W^^V^^kk'^k^kk^W'.^k^^k^W^'-^VW^kk^k^.^^'.W'.W 



COMPRES.SORS 



BRINE TAMK 



■^"■•""'■i'""^'""^'^ 



I MEN.'5 
LOCKER 
I ROOM 



ICE MAKIMQ 
TAAKS 



COMPRESSORS 



ICE STORAGE 
ROOM 



/ 



-ICE CRVSHER-s 
-ICE ELEVATOR- 



ELEVATOR ^ 



m\\\\\\\\\^\\^\^^ 



;^\\\\\\NW 



Fig. 84. — Basement plan of large ice-cream plant. 



The exact location of the machines is not indicated, 
since this will depend on their size. However, the rooms 
are large enough so that the exact placing of the machines 
is not a difficult problem. 

The basement, first and second floor plans of a whole- 
sale plant are shown in Figs. 84, 85, 86, For the reasons 
previously mentioned, the exact location of the machines 
is not indicated. 



CONSTRUCTION OF FACTORY 



275 



5 lit) 



■/' 



en/r,3nce 



." .^ I ' ■ '. . 1=T~ 



TUB STORAGE 



Sdn^/n 



express shipmen/s 



^ FREEZING 

•;^<?yo/l//n^ doors for p^c A c<^ns^ 



/ 



ANTE ROOM M 



^rS^ 



g!5 

si 

a:: 



=SF 



rHF 



^=S,F 



ANTE ROOM 



SxVvVV'W^I tt-S.V\V\\\\\\\\- 



gj PLATPORM 



ICE SHVTE 

SfJippim/ door | — ^ 

:^'^'^?^ l.'^^^\v;^v .^''^^' 



^^ 



■^ CAN STORAQE 

AND 
t$i WASNINQ ROOM 






^'-vvv'^'t i-'-^^w 



scALt IN mcr 



<^E SHVTE 

' r^ — I shipping door 



ELEVATOR 



Fig. 85. — First floor plan of plant shown in Fig. 84. 







OF-PICE 



SCALE IN FC£T 



^^^ 



LADIE'S ^ 
SRESTROONI LABORAToRil 



NLXINQ ROOM 



PASTEVRIZINQ, 
CLARIEYI/VJO 

OR 



BVNKER ROOM 



EMVLSIPYIAC 
' ROOM 



% 



Uk'm k i k k I k kUk k k k^k k k< ft^ kk\ < k k\yi,>.y.fi 



CREAM 
STORAGE 



' drsin 



^vv^v^s.'^ — Kvvvvw^!! — tmv\m\;^w^'s<\s^s\(m^v^^lw^^^ — :-4sV\\vv\^:^?;;^^^:;:;^^ 



ElEVATOR 



Fig. 86. — Second floor plan of plant shown in Figs. 84 and 85. 



276 THE BOOK OF ICE-CREAM 

210. Loading platform. — There should be ample room 
for the loading of the ice-cream and the unloading of the 
empties and the returned ice-cream. The loading plat- 
form should be protected from the storms. Such a plat- 
form in a large ice-cream plant is shown in Fig. 87; note 
the chutes for the loading of crushed ice. Often the wagon 
or auto storage is a part of the same space as the loading 
platform. 

211. Light. — The question of proper light in the ice- 
cream plant has been neglected. This may be because 




Fig. 87. — A loading platform in a large ice-cream plant. 

the buildings in the city are close together and it. is diffi- 
cult to get light except from the ends of the building 
which are exposed to the street or alley. Many of the 
smaller plants are in the basement and in these it is im- 
possible to have anything but artificial light. The natural 
light may be secured from windows or skylights. The 
sacrifice of space for skylights is shown in Fig. 88. Light 
seems to be a stimulus to keep the plant clean. It also 
makes it more pleasant and cheerful. It is believed that 
sunlight tends to disperse disease germs. It would 
be a great benefit if it were necessary for all ice-cream 



CONSTRUCTION OF FACTORY 



277 



plants to have a certain amount of window space in each 
room. 

212. Ventilation. — Next to Hght, the question of proper 
ventilation is neglected. The windows, doors and sky- 
lights may serve as a means. If they are used for this 
purpose and are screened against flies, there is danger of 
considerable dirt getting in. In some of the large plants. 




Fig. 88. — The value of skylights is shown by this well lighted freezing- 
room, considerable floor space above being sacrificed for this purpose. 

a very extensive system of ventilation is employed. In 
these, no air is allowed to enter except through this system, 
and all the entering air is either filtered or washed or both. 
The air is circulated by a large fan. This insures only 
clean pure air entering the manufacturing rooms. The 
importance of pure air about food products cannot be 
over-emphasized. It is difficult to ventilate a basement 
properly. All doors and windows should be screened 
against flies. There should be no stable in connection 
with the manufacturing rooms. 



278 THE BOOK OF ICE-CREAM 

213. Floors. — The floors should be of some non-absorb- 
ent waterproof material that can be cleansed easily. 
Concrete undoubtedly is the best material, when both 
cost and adaptability are considered. The floor should 
slope towards drains which will carry away the water. 
These should be connected with the city sewage system, 
septic tank, or cesspool. If sewage connections cannot 
be obtained, a cesspool or septic tank must be installed, 
preferably the latter. The drains should have sealed 
traps to prevent the escape of sewage gas into the plant. 
Some prefer to have the drain in the center of the floor 
and others at the side; this is immaterial so long as it 
works effectively. 

214. Ceilings and side-walls. — The ceilings and side- 
walls should be kept clean. If they are constructed of 
various tiles or plasters, they can be washed. If made of 
wood, they should be kept painted. If painted white or 
light colored, it helps to make the room lighter. 

215. Sinks and cupboards. — Proper facilities should be 
provided properly to wash and sterilize the utensils. There 
is usually a lack of sinks for washing utensils in the ice- 
cream plants. After the utensils are properly cleaned, 
there should be a place where they can be kept until 
wanted again. Tables, shelves, and cupboards offer suit- 
able places to keep utensils when not in use. 

216. Locker-rooms. — Every plant where food prod- 
usts are manufactured should be provided with a locker- 
room in which the employees can change their clothes. 
Each person should have a separate locker. The locker- 
room should also contain a lavatory and shower-baths 
and facilities for washing the hands and face. The locker- 
room should be kept neat and clean. 

217. Cleanliness. — The average consumer appre- 



CONSTRUCTION OF FACTORY 279 

ciates food products produced in clean plants. There is 
no better advertisement than to invite the public to see 
the factory. The plant and employees should be so clean 
that it will make a strong impression and the visitors in 
turn will tell others. The employees should wear clean 
white suits-. If the plant is large enough, a laundry for 
washing may be included in the equipment. 

218. Cleaning utensils. — Few ice-cream-makers know 
how to clean the utensils thoroughly. The following is a 
good method: (1) Rinse off the milk and grease with 
lukewarm water. (2) Wash in hot water as hot as the 
hands can stand. To this water add some washing- 
powder to cut the grease. There is a tendency to use too 
much washing-powder. Enough to burn the hands. should 
not be used. (3) Scrub the utensils in the washing solu- 
tion with a brush. Do not use a cloth. (4) Rinse with 
warm water. (5) Scald with boiling water or live steam. 
The utensils may be dipped in boiling water or boiling 
water may be poured over them. They may be placed in 
a sterilizer and live steam applied. The heating kills most 
of the bacteria and is usually sufficient to dry the utensils. 
In no case should a cloth be employed for drying. 

219. Cleaning the floor. — The proper cleaning of the 
floor is not considered by many as a necessary part of 
the manufacturing process. However, it is very impor- 
tant in the clean appearance of the plant that the floor 
be clean. Often too much water is used and yet the floor 
is not clean. The best method is as follows: (1) Rinse 
the floor with water thrown from a pail; (2) sweep up all 
loose dirt; (3) make a hot solution of washing-powder, 
a little stronger than for washing utensils, and spread 
this on the floor and scrub with floor broom, scrub toward 
the drain; (4) rinse with clean warm water thrown from 



280 THE BOOK OF ICE-CREAM 

a pail. If the hose is used, too much time and water are 
wasted. 

220. Storeroom and workshop. — No ice-cream plant 
is complete unless it includes a storeroom and workshop. 
More or less supplies must be stored and it helps the 
general appearance of the plant materially if there is a 
special room for this purpose. More or less repairs are 
necessary, so that a workshop should be provided. It 
is desirable to have this near or a part of the storeroom. 

221. Sanitary codes. — ^Many states have ice-cream- 
makers' organizations or associations. The state organ- 
izations are united in a National Association of Ice- 
Cream-Makers. Many of these associations have adapted 
sanitary codes. Following are some samples: 

Ohio sanitary code: 

1. All factories or shops shall be open to the public at 
all times. 

2. Workrooms must be thoroughly clean and free 
from dust, foul .atmosphere and contamination, and shall 
be well lighted, to the end that there shall be no dark 
corners where rubbish or dirt may accumulate. 

3. One square foot of glass surface exposed to natural 
light, unobscured by buildings or other devices nearer 
than ten feet, for each ten square feet of floor surface of 
the workrooms must be provided. Basements shall not 
be used as workrooms unless these provisions can be met. 

4. Garbage and all waste material subject to decom- 
position, must be removed daily to the outside and de- 
posited in a can provided exclusively for this purpose, 
composed of impervious material and provided with a 
tight fitting cover. Covers must be kept on the cans at 
all times except when entering or removing the material. 

5. The side-walls and ceilings of all workrooms shall be 



CONSTRUCTION OF FACTORY 281 

well plastered, tiled or wainscoated or ceiled with metal 
or lumber and shall be well painted to the end that they 
may be readily cleaned and they shall be kept free from 
dust, dirt and foreign matter and clean at all times. 

6. The floors of all workrooms shall be impermeable 
and be made of cement, tile laid in cement, or other 
suitable non-absorbent material which can be flushed 
and washed clean with water. Floors shall be sloped to 
one or more drains which must be properly connected to 
the sewerage system. 

7. Store and storage rooms for materials must be kept 
clean and free from objectionable odors. 

8. Doors, windows and other openings of every work- 
room shall be screened during the fly season with screens 
not coarser than 14-mesh wire gauze, or in any other 
manner equally effective keep the workrooms free from 
flies and vermin at all seasons of the year. 

9. All factories or shops shall have convenient toilet 
rooms, separate and apart from the workrooms, and no 
toilet rooms shall be within or connected directly with a 
workroom, either by a door, window or other opening. 
The floors of the toilet room shall be of cement, tile or 
other non-absorbent material, and shall be kept clean at 
all times. Toilet rooms shall be furnished with separate 
ventilating flues or pipes discharging into soil pipes or on 
the outside of the building in which they are situated. 
Lavatories and washrooms shall be adjacent to toilet 
rooms and shall be supplied with soap, running water and 
clean towels and shall be maintained in a sanitary con- 
dition. Workroom employees before beginning work and 
after visiting toilet rooms shall wash their hands and armis 
thoroughly in clean water. 

10. No person shall live or sleep in any building used 



282 THE BOOK OF ICE-CREAM 

as a factory or shop, unless the factory or shop is separated 
by impervious walls, without doors or windows or other 
openings from the parts of the building used for living 
or sleeping purposes. 

11. No horses, cows or other animals shall be stabled 
or kept in any building where ice-cream is made, unless 
the factory or shop is separated from the place where the 
horses, cows or other animals are stabled or kept by 
impervious walls without doors, windows or other open- 
ings. 

12. No person suffering from an infectious disease, 
which can be transmitted through ice-cream, shall work 
in an ice-cream manufacturing plant. 

13. All workroom employees shall be clean in person 
at all times and shall wear clean washable clothing and 
caps. They shall not smoke or chew tobacco while at 
work. They shall not touch the product with their hands 
at any time. Employees may be specially designated to 
cut and wrap brick ice cream and to fill fancy moulds and 
as this work necessitates some handling of the product, 
such employees must be scrupulously clean and wear 
clean, washable clothing and caps. 

14. All wagons, trucks, drays, cans and tubs, plat- 
forms and racks, shall be so constructed that they may 
readily be cleaned and they shall be kept clean. Utensils 
must be of smooth non-absorbent material, as tin, or 
tinned copper, the seams of which are flushed smooth 
with solder. 

15. Suitable means or appliances shall be provided for 
the proper cleansing or sterilizing of freezers, vats, cans, 
mixing cans or tanks, piping and all utensils used as 
containers for ice-cream or raw material, and all tools 
used in making or the direct handhng of ice-cream, and 



CONSTRUCTION OF FACTORY 283 

all such apparatus, utensils, and tools after use shall be 
thoroughly cleansed and scalded with boiling water or 
sterilized with steam. The water supply for washing 
utensils must be free from contamination. 

16. No person shall use any vessel used in the manu- 
facture and sale of ice-cream for any other purpose. 

17. Soft or melted ice cream or any other ice-cream 
shall not be refrozen under any circumstances. 

18. Milk and cream must be stored only in clean re- 
ceptacles in clean refrigerators. Milk or cream which has 
undergone various fermentations, gaseous, bitter or other- 
wise, shall not be used in the manufacture of ice-cream. 
Flavoring extracts, condiments, syrups, fruits, nuts and 
other materials used as food must be securely protected 
from dust, dirt, vermin, flies and other contamination, 
and must be kept and stored only in clean receptacles. 
Decomposed, decayed, fermented or rancid food material 
shall not be used. Ice-cream must be stored only in clean 
receptacles in clean refrigerators. 

19. It is expressly declared that the object of this code 
is to insure a pure and clean product, made, stored and 
handled under clean conditions, and no technical defect 
in the construction of any clause shall relieve any person 
of the obligation of complying with the letter and spirit 
of this code in its entirety. 

20. All creamery and condensery operators, ice-cream 
manufacturers and all other dealers in milk and cream, 
and their customers must cleanse all receptacles used in 
shipping milk and cream as soon as they are emptied, 
when same are to be returned by railroad, trolley, or 
boat, in order to prevent the development of dangerous 
bacteria to threaten the health of the consumers of the 
product. 



284 THE BOOK OF ICE-CREAM 

Sanitary code of the association of ice-cream manufacturers 
of New York state. 

1. All factories or shops shall be open to the public at 
all times. 

2. Workrooms must be thoroughly clean and shall be 
well ventilated and well lighted to the end that there 
shall be no dark or concealed corners where rubbish or 
dirt may accumulate. 

3. The- side-walls and ceilings of all workrooms shall be 
well plastered or tiled or ceiled with metal. If plastered or 
ceiled with metal, they shall be kept well painted with 
oil paint to the end that they may readily be cleaned and 
they shall be kept clean at all times. 

4. The floors of all workrooms shall be impermeable 
and be made of cement, tile laid in cement, or of other 
suitable non-absorbent material which can be flushed and 
washed clean with water. Floors shall be sloped to one or 
more drains which must be properly connected with the 
sewerage system. 

5. Storerooms for materials shall be kept clean and free 
from objectional odors. 

6. Doors, windows and other openings of every work- 
room shall be screened during the fly season, and all work- 
rooms and storerooms shall be kept free from flies at all 
seasons of the year. 

7. All factories or shops shall have convenient toilet 
rooms separate and apart from the workrooms, and no 
toilet room shall be within or connected directly with a 
workroom either by a door, window or other opening. 
The floors of the toilet rooms shall be of cement, tile or 
other non-absorbent material, and shall be kept clean at 
all times. Toilet rooms shall be furnished with separate 
ventilating flues or pipes, discharging into soil pipes or on 



CONSTRUCTION OF FACTORY 285 

the outside of the building in which they are situated. 
Lavatories and washrooms shall be adjacent to toilet 
rooms and shall be supplied with soap, running water and 
clean towels, and shall be maintained in a sanitary condi- 
tion. Workroom employees beginning work and after 
visiting toilet room shall wash their hands and arms 
thoroughly in clean water. 

8. No person shall be allowed to live or sleep in any 
building used as a factory or shop, unless the factory or 
shop is separated by impervious walls, without doors or 
windows or other openings from the parts of the building 
used for living or sleeping purposes. 

9. No horses, cows or other animals shall be stabled or 
kept in any building where ice-cream is made, unless the 
factory or shop is separated from the places where the 
horses, cows or other animals are stabled or kept by im- 
penetrable walls without doors, windows or other open- 
ings. 

10. No person suffering from an infectious disease, 
which can be transmitted through ice-cream, shall be em- 
ployed in an ice-cream manufacturing plant. 

11. All workroom employees shall be clean in person at 
all times and shall wear clean, washable clothing and caps. 
They shall not smoke or chew tobacco while at work. 
They shall not touch the product with their hands at any 
time. Employees may be specially designated to cut and 
wrap brick ice-cream and to fill fancy molds, and as this 
work necessitates some handling of the product, such 
employees must be scrupulously clean, and wear clean, 
washable clothing and caps. 

12. All wagons, truck, drays, cans and tubs, platforms 
and racks shall be so constructed that they may be readily 
cleaned, and they shall be kept clean. 



286 THE BOOK OF ICE-CREAM 

13. Suitable means or appliances shall be provided for 
the proper cleansing or sterilizing of freezers, vats, mixing 
cans or tanks, piping and all utensils used as containers for 
ice-cream, and all tools used in making or the direct hand- 
ling of ice-cream, and all such apparatus, utensils and 
tools after use shall be thoroughly cleansed and rinsed with 
boiling water or sterilized with live steam. 

14. Vessels used in the manufacture and sale of ice- 
cream shall not be employed for any other purpose by any 
person. 

15. No member shall take back any broken package of 
ice-cream, nor any unbroken package which contains 
soft or melted ice-cream. No ice-cream shall under any 
circumstances be melted and refrozen. 

16. It is expressly declared that the object of this Code 
is to insure a clean product, made, stored and handled 
under cleanly conditions, and no technical defect in the 
construction of any clause shall relieve any member of the 
obligation of complying with the letter and the spirit of 
this Code in its entirety. 



CHAPTER XVII 
HISTORY AND EXTENT OF THE INDUSTRY 

The history of the development of the ice-cream indus- 
try is only fragmentary. This may be because the in- 
dustry has developed very gradually. Exact figures 
showing the size of the industry are lacking, no authentic 
figures ever having been brought together. The facts 
relating to the history of the industry have been gathered 
and very well put together by F. M. Buzzell, in an article 
in the " Ice-cream Trade Journal," Vol. 5, No. 3. The 
history as given here is a copy of the above article. 

222. Early history. — *'From motives of comfort and 
health, the instinct of man in all ages and climates has 
been to maintain his physical (if not his mental) being at a 
temperature as nearly normal as possible. Thus we find 
the natives of Iceland and other very cold climates living 
upon heat-producing foods, fats, tallow candles, and such 
delicacies, while the South Sea Islander lunches on a little 
fruit or cereal, or other food producing a minimum of 
bodily heat. This rule applies also to liquid refreshment. 
Hot weather creates a demand for cooling drinks, and vice 
versa. And we, in our day, when we sit in the coolest 
spot to be found on some sweltering August night, and 
sip our favorite cold drink, are actuated by the same mo- 
tive which has influenced our ancestors from the more 
recent past back to the days of Job and Solomon the Wise. 
For the Bible tells us indirectly that the people of Palestine 
knew and appreciated the refreshing quality of snow in 

287 



288 THE BOOK OF ICE-CREAM 

time of harvest. The Jews, the ancient Greeks and 
Romans were all accustomed to the use of snow for cooling 
wines and other beverages, and it is to-day used in this 
way in certain parts of Spain and Turkey. 

''Only those southern localities which were favored with 
the proximity of snow-capped mountains could enjoy the 
luxury of a snow-cooled beverage or dessert. Where snow is 
not obtainable, liquids were, and still are, cooled in porous 
jars, and urns exposed to cool breezes, or, in lack of a 
breeze, swung about to create a current of air. The 
principle is a familiar one. The most common method of 
preserving snow was to saturate it with water, having 
packed it closely into some receptacle, of considerable size 
probably, and allowing it to freeze into a kind of porous 
ice, from which blocks could be cut as required for use. 
To chill a dessert or a liquid, the dish containing it was 
imbedded in a larger vessel partly filled with snow and 
particles of ice, and the open space closely packed with 
it. It was then allowed to stand until it had become as 
cold as possible or as desired. 

"Alexander the Great is said to have been very fond of 
iced beverages, and one of our modern varieties, the 
Macedoine, it is said, was named for the great Macedonian. 
Snow and ice were used at the table in the court of Henry 
III of France in the hot summer months. The Italians, it 
is claimed, made the first improvement in the original 
method of cooling, which improvement was to dissolve 
saltpetre in water and pour a little of the solution in with 
the snow and ice surrounding the dish to be cooled. Later, 
it was found that better results were attained by dropping 
the saltpetre directly into the snow and ice, and at the 
same time revolving the vessel containing the substance to 
be chilled. By this means the mixture in the vessel could 



HISTORY AND EXTENT OF THE INDUSTRY 289 

be brought to a fairly solid state. Wines were commonly 
iced in this way, then water, sweetened and flavored with 
various juices or other flavorings, was made into a sort 
of water ice. Water ices and such refreshments are still 
the rule in the Orient, while ice-cream, as we know it, is 
rare. 

^' There is no reliable record of the first water ices. 
Dates and places are either lacking altogether in the vague 
allusions made to them or are so indefinite as to be of no 
value. It is probable that they were brought to France 
from Italy by Catherine de Medici, who preferring cookery 
to which she was accustomed, brought her staff of cooks 
with her. The date is given as about 1550. Water ices 
are said to have been made by Contreaux, an Italian who 
established a famous cafe in Paris. Lemonade was in- 
vented about 1630: to whom the credit belongs is not 
known. From water ices to mixtures containing milk or 
cream and eggs, was apparently a logical progression, but 
history is vague on the question of who first made ice- 
cream." 

223. Development of ice-cream in the household. — 
*'It is recorded that in Rome, a certain Quintus Maximus 
Gurges, nicknamed 'The Glutton,' a well known writer 
of those times on subjects pertaining to the table wrote a 
recipe in one of his books for a dish that somewhat re- 
sembled ice-cream. The name ice-cream is one of modern 
origin, the original terms being butter ice, or cream ice, 
the latter being to-day favored in England. The earlier 
forms, after the ices containing milk or cream, which were 
really the first ice-creams known, were called butter ice 
probably because of their rich butter-like consistency, 
being made from rich cream and spaddled. Cream ice is 
said to have been known in Paris in 1774. Recipes for 



290 THE BOOK OF ICE-CREAM 

water ices and milk ices, it is claimed, were brought from 
Asia by Marco Polo, who visited Japan in the fifteenth 
century. Cream ice is mentioned in an account of a 
banquet given by Charles I, of England. The dish was 
made by a French cook named De Mireo, and it is related 
that the king was so well pleased with the 'frozen milk,' as 
he called it, that he pensioned the cook with twenty 
pounds a year on condition that he would not divulge the 
secret of making the dessert, nor make it for anyone but 
him. Another account says that the first ice-cream was 
set before the Due de Chartres on a hot day in August, 
1774, by his chef, who had depicted the duke's coat-of- 
arms on the cream. Again we find in an account of an 
entertainment given by Louis XIV, of France, that 
' toward the end of the feast, his chef caused to be placed 
before each guest, in silver gilt cup, what was apparently a 
freshly laid egg, colored like those of Easter, but, before 
the company had time to recover from their surprise at 
such a novelty at dessert, they discovered that the sup- 
posed eggs were a delicious sweetmeat, cold, and com- 
pact as marble.' It is also claimed that a certain Carlo 
Gatti first introduced cream ices into England. 

"A French cook, Clermont, residing in London, gave 
instructions for making sweet ices in a book he published 
in 1776. English cook books one hundred and fifty years 
old give recipes for cream ices in which cream and milk, 
sugar, eggs, arrowroot or flour and flavoring were used. 
Recipes have always varied according to the whim or 
desire of the maker, and there is no similarity in the 
amounts of cream or milk to be used. 

"It is. a question whether Germany or England first 
made ice-cream, but it is generally conceded that the 
Germans led the English in making fancy moulded creams. 



HISTORY AND EXTENT OF THE INDUSTRY 291 

''We deduce from the foregoing bits of narrative that 
ice-cream was not apparently discovered, but rather was 
the result of a slow process of evolution or development, 
which was taking place in different localities at about the 
same time. History states that ice-cream was first sold 
in New York by a Mr. Hall, at 75 Chatham street, now 
Park Row. Ice-cream is mentioned in an account of a 
ball given by a Mrs. Johnson, December 12, 1789, and was 
introduced to the city of Washington by Mrs. Alexander 
Hamilton at a dinner at which President Jackson was 
present. She had become familiar with the dish in New 
York. The first advertisement of ice-cream appeared in 
a New York paper, the Post Boy, dated June 8, 1786, 
and reads as follows: 'Ladies and gentlemen may be 
supplied with ice-cream every day at the City Tavern by 
their humble servant, Joseph Crowe.' A negro, one 
Jackson who had worked at the White House in Washing- 
ton after Mrs. Hamilton introduced ice-cream to Presi- 
dent Jackson, learned the recipe and started a confec- 
tionery. He sold his cream readily at one dollar per 
quart. Others imitated him, but Jackson held his custom 
and prospered by making the best goods and died 
wealthy." 

224. Development of wholesale ice-cream. — ^' Jacob 
Fussell is admitted to be the father of the wholesale ice- 
cream business. The year 1851 found him in the milk busi- 
ness at Baltimore. His supply of milk came into Baltimore 
on the Northern Central Railway from York county. Pa. 
A few of his customers wanted cream, and finding that 
satisfactory results were not obtained by ordering cream 
intermittently to supply an unsteady demand, he made 
arrangements for a regular shipment. Here again a diffi- 
culty presented itself, for at times he found his stock of 



292 THE BOOK OF ICE-CREAM 

cream accumulating, which must be disposed of in the best 
way possible. To utilize this surplus he conceived the 
idea of making ice-cream, the retail price of which at 
this time by the few confectioners who sold it was sixty 
cents per quart. The idea proved an inspiration, for the 
ice-cream business soon overshadowed the milk business, 
which was in time disposed of. Mr. Fussell believed in 
the value of printers' ink and advertised his new business, 
and then, as now, intelligent advertising paid. Devoting 
his entire attention to the ice-cream business, he prospered 
in it, and built up a large business, the success of which 
has continued through three generations to the present 
day. In 1852 and 1853 he tried out a scheme for making 
his ice-cream at the source of supply of his raw material, 
rather than at the distributing point, but it did not prove 
successful, for while the ice-cream was actually produced 
cheaper in the country, the fact that his own attention 
was divided between the two establishments, and that 
the stock at the selling end could not be readily controlled, 
counteracted the lesser manufacturing cost, and the re- 
sult was that the project was abandoned and not repeated. 
In 1856 the Baltimore business was left with a partner 
and a factory was opened in Washington, D. C. In 1862 
Boston was added to the chain of plants. Here a large 
exporting firm, who had made considerable money shipping 
ice to London, India, and Brazil, saw a new outlet for ice 
in the ice-cream business. They attempted to induce Mr. 
Fussell to go to Brazil and start a factory there, and offered 
to back him with the necessary capital if he wanted it, 
but he was not interested. Failing to get him to send one 
of his men over, they arranged for one of their own men 
to learri the art of making ice-cream, and paid a modest 
1500 for the formula. How the South American venture 



HISTORY AND EXTENT OF THE INDUSTRY 293 

fared is not recorded. In 1864 the New York house of 
Fussell was started and continued with the usual success. 
Here the prevaihng price among confectioners was $1.25 
per quart. A Mr. Brazleton, of Iowa, a friend of Mr. 
Fussell, losing his fortune in the panic of 1857, came to 
Washington and learned the ice-cream business. He went 
back west and opened a factory in St. Louis, later going 
to Cincinnati and Chicago. 

"American enterprise was not long in taking up the 
new industry, and the growth of the business had com- 
menced. However, the real development, the day of 
large figures in the business, had its beginning not over 
fifteen years ago. The brine or refrigerating system of 
freezing ice-cream has been efficiently applied only within 
the past five years, and has now only fairly begun. 

"The first real progress toward artificial refrigeration 
is said to have been made by a German in 1867, and it 
was then used only in breweries, and to a very limited 
extent. Ice making by artificial means came next. The 
use of refrigerating processes for making ice-cream was 
probably begun in a way by chance, for large ice manu- 
facturing establishments put on an ice-cream department 
to utihze the broken or waste ice, and the possibility of 
applying mechanical refrigeration to the making of ice- 
cream was no doubt thus discovered. 

"Ice-cream is not today, as in past years, a luxury. 
Its lowered cost brings it within reach of the masses: no 
longer is it something which may be enjoyed only by the 
rich. It is fairly entitled to a place in the class of neces- 
sities. Ice-cream is in high favor in England, where the 
climate favors its use the year through. And it is used 
by nearly all steamship fines, especially those making 
long trips in warm climates. The passengers, who do 



294 THE BOOK OF ICE-CREAM 

not relish the indifferent quality of most foreign made 
goods, demand American ice-cream. Every express 
steamer of the North German Lloyd Line leaves New 
York with not only a supply to care for the wants of its 
own passengers, but enough to furnish the Japanese, 
Chinese, and Australian service of the company. For the 
far eastern service the cream is carried in refrigerated 
compartments to Bremerhaven and there transferred to 
ships sailing for ports in India, China, Japan and Australia. 

'^It does not seem proper to close this paper without 
some allusion to our friend of the lawn party, ice-cream 
wagon, and county fair — the ice-cream cone. I have 
heard that it was introduced in this country at the St. 
Louis exposition. I have found directions for preparing 
a refreshment called 'fried ice-cream,' sometimes known 
as 'Alaska pie,' or 'Alaska fritters.' The method is, 
briefly to dip a cube of hard ice-cream into a thin fritter 
batter and then plunge it into very hot lard or olive oil. 
The pastry forms a good protector from the heat and 
hardens so quickly that the cream is not softened in the 
least. Another more elaborate form is said to be served in 
certain New York cafes today. The fried ice-cream was 
introduced at the World's Fair in Chicago in 1893. It 
occurred to me that these freak varieties may have sug- 
gested the idea of the ice-cream sandwich and ice-cream 
cone. Whatever the origin, we will have to admit that 
the cone has sold many a gallon of ice-cream and made 
many a 'dollar for those engaged in the business. 

"And I believe that the future historian of this business, 
who shall recount the progress of its development during 
the years from 1900 to 1910, cannot but remark upon that 
decade as being epoch making in the annals of the trade." 

225. Extent of the industry. — While no census figures 



HISTORY AND EXTENT OF THE INDUSTRY 295 

of the industry have ever been assembled, careful esti- 
mates and surveys have been made by both T. D. Cutler 
of the ''Ice-Cream Trade Journal" and L. O. Thayer of 
the " International Confectioner." The results of these 
surveys are shown in Table XIV. In comparison to the 
value of ice-cream, the 1910 census gives the follow- 
ing values for the year 1909, for butter, cheese, and con- 
densed milk; value of all dairy products, $596,413,463.00; 
value of butter, cheese, and condensed milk made in fac- 
tories, $274,557,718.00; total investment in equipment, 
$71,283,624.00. Regarding the distribution of the whole- 
sale plants in the United States, the North Atlantic states 
have the most, with the Middle West a close second. 
The production of ice-cream in the South is growing very 
rapidly. This is possible because of the homogenizers 
and emulsifiers and mechanical refrigeration. 



296 



THE BOOK OF ICE-CREAM 



o o o 

o o o 

R o o 

eo' o" fo" 

Tf< T-H IC 

(N 00 O 

■ 00 in" -j" 

eo 05 CO 

tH <n 



o 
o 
o 
o" 
»o 
o 

05 






o 

^ 

+= 



03 



o 

• I— I 

o 

O 



o o o 

o o o 

o o o_ 

co" ci lO" 

CO lO 00 

1-1 N CO 



o o o 

00 O 00 



-t-3 


^ C5 05 

^ <N CO_ 


c3 


0' 00" 00 


m 


TJH CD 



000 

01 O 05 

CO ■>* o 

r>r in' o 

CO 00 ic 

t> o 10 



p^ 2 



000 

000 
000 

o' o" o" 

000 
000 



000 
000 
000 

o" o" o* 
000 
000 



00 



o 

CO 

d 

o 

co" 
CO_ 

05 
IN- 



O 
O 

o 

o" 
10 

co" 



o 

o 
o 

o 
o 

CO 
CO 
00 



o o 

O'O 

o o 
o" o" 

■* IM 





d 



















§ 


§ 




7-^ 







q_ 


^ 






Tt< 





hH 


B 


-* 

5 


0" 


t-h" 


CO 




10 


CI 




10" 

CO 


0" 



^ 


OS 





10 

(N" 


CO 




00 


IN 

05" 


co" 







CO 


CO 
1—1 


CO 

l-H 






(N 
<N 


1> 


P5 


[ 




d 


d 


^ 






d 


d 


l-H 












§ 














< 


*<-< 


eo 













5 





c^ 





H 







03 


16 


00 

CO 


00 

co_ 
in" 




00 


CO 
CO 





00" 






CO 


CO 


I> 






rt< 


CO 



<=■ 2 
<=> 2 
o o 



*- fe ^ S - 

=^113 1 

£ P O ^ 



0} a; 



C 

o 



c3 (D 

o > 



— ai 






- .9 = 






^^M 



fl.S s 

-w Q 03 cj 
03 03 O S aj 
> ft {4 tf >^ 



P^ 



INDEX 



Acid-coagulating group, 175 
Acid-forming group, 175 
Acid test, 200 
Adulterated ice-cream, 4 
Advertising, 255 
Alexander, Jerome, 248 
Ammonia machines, 116 
Andels, 101 
Automobile truck, 251 
Available refrigeration, 110 
Ayres, S. H., 11, 21 
Ayres, S. H., and Johnson, W. 
T., Jr., 175 

Babcock test, 183-197 

cream, 192 

laws, 266 

modifications of, 197 

skim-milk, 196 

whole milk, 183 
Bacilli, colon, 181 
Bacteria, 15, 170 

acid-coagulating group, 175 

acid-forming group, 175 

alkali group, 178 

conditions for growth, 16 

effect of temperature, 20 

forms of, 16 

freezing and hardening, 174 

inert group, 177 

number of, 171 

peptonizing group, 179 

prevention of growth, 18 

sources of, 170 

total acid group, 175 

types of, 175 

utensils, 174 



Bacteriology, problems of, 181 

study of, 181 
Baer, A. C, 139, 163 
"Batch," 129 
Baume scale, 27 
Benkendorf, G. H., 213 
Benkendorf test, 213 
Binders, 51 

effect of, 167 
Bisque ice-cream, 73 
Boiled milk test, 203 
Brainard, W. K., 167 
Brick-cutting machine, 159 
Brick molds, 159 
Bricks, 145 
Brine Idox, 148 

freezer, 84 

tanks, 119 
British thermal unit, 101 
Bookkeeping, 258 
Bowen, John T., 101, 107, 111 
Butter, 41 
Butter testing for fat, 205 

moisture, 205 

salt, 207 
Buying materials, 257 
Buzzell, F. M., 287 

Cabinet, 253 
Can washerSj 95 
Caramel ice-cream, 72 
Carpenter, M. R., 151 
Census figures, 295 
Chocolate and cocoa, 46 

adulteration of, 49 

composition, of, 48 

manufacture of, 47 



297 



298 



INDEX 



Chocolate and cocoa, standard 

for, 48 
Chocolate ice-cream, 72 
Chocolate sirup, 49 
Clarifier, 22 
Cleanliness, 278-280 
Clemner, P. W., 21 
Coffee ice-cream, 72 
Colloids, 249 
Color, 132 
Composition, 249 
Compressor, 117 
Condensed milk, 25 

marketing, 31 

method of manufacture, 25 

purchase of, 28 

standard for, 27 
Condenser, 27 
Condensing coils, 117 
Condensory, 28 

amount of milk necessary, 29 

capital necessary, 31 

condition of milk, 30 

location, 31 

supply of milk for, 29 

supply of water for, 29 
Cook, L. B., 21 
Cooked ice-cream, 70, 74 
Cooling milk and cream, 18 

methods of, 19 
Cooper, Madison, 101 
Corbett, L. C, 104 
Corn sirup, 45 
Corn starch, 55, 70, 76, 77, 

169 
Coumarin, 64 
Cow, food for, 13 

health of, 14 
Cream, composition of, 23 

emulsified, 41 

homogenized, 41 

standard for, 24 
Creamers, 95 
Crystallization, 167 



Custards, 76 
Cutler, T. D., 295 

Dairy products, legal standards, 
267-271 

Defects, 165 
appearance, 169 
body and texture, 166 

Defects, flavor, 165 
package, 169 
richness, 169 

Defrosting the coils, 151 
air blast system, 154 
cold brine drip system, 153 
Cooper system, 151 
hot brine system, 154 
hot gas system, 155 
warm liquid system, 155 

Delivery, cost of, 252 
method of, 250 
packages used, 252-254 

Disc-freezer, 89 

Disease, 250 

Dishes, 254 

Eggs, 55 

Ekenberg Co., 39 
Ekenberg process, 39 
EUenberger, H. B., 139, 172, 

175 
Emery Thompson freezer, 87 
Emulsors, 95, 141 

advantage of, 99 
Emulsified milk and cream, 10, 

13 
English plum pudding, 76 
Equipment, 81 

cost of, 100 
Evaporated milk, 25 
Evaporating coils, 118 
Expansion valve, 118 

Factory, construction, 272 
floors, 278 



INDEX 



299 



Factory, light, 276 

location of, 272 

plans, 273-275 

ventilation, 277 
Fat, churned, 166 
FiUers, 51 

starchy, 55 
Flavors, 2 

Flavoring extracts, 57 
Food value, 247-250 
Formaldehyde test, 203 
Formulas, 45, 71 
Fort Atkinson freezer, 88 
Frandsen, J. H., 45 
Frandsen, J. H., and Markham, 

E. A., 69, 163 
Freezers, 81 

brine, 84 

disc, 89 

Emery Thompson, 87 

Fort Atkinson, 88 

hand, 83 

Perfection, 85 

Progress, 86 

tub and can, 83 
Freezing process, 134 

effect of sugar on, 137 

proper method of, 137 

purpose of, 134 

rate of, 134, 137 
Fruit, 132 

extracts, 68 

ice-cream, 73 

pudding, 76 
Fussell, Jacob, 291 

Gelatine, 52, 132, 168 

food value, 249 

kettle, 53, 91 

preparation of, 53 

tests for, 52 
Gum tragacanth, 132 
Guthrie, E. S., and Ross, H. E., 

204 



Hammar, B. W., 172, 173, 174 
Hammar, B. W., and Goss, 
E. F., 172 

Hand freezer, 83 
Hardening, 91, 145 

effect on quality, 157 

forced-air, 149 

gravity-air, 149 

ice and salt box, 146 

method of, 145 

time required, 157 
Hardening-room, 149 

still-air, 149 
Heat, sensible, 102 

latent, 102 

specific, 102 
History, 287-289 
Holdaway, C. W., and R. R. 

Reynolds, 167, 215 
Homogenizers, 95, 141, 167 

advantage, of 99 
Homogenized milk and cream, 

10, 13 
Horses and wagons, 251 
Hot well, 26 
Hunziker, O. F., 183 

Ice, amount needed, 107 

field, 103 

saw, 106 

storing and harvesting, 105 
Ice and salt mixture, 107 

amount used, 148 
Ice-cream, appearance, 164 

bacterial count, 164 

body and texture, 164 

classification of, 69 

color, 2, 73, 132 

composition of, 249 

definition of, 2 

demand for, 12, 246 

desired standard, 5 

factory development, 291 

fancy molded, 158 



300 



INDEX 



Ice-cream, Federal standard, 

2 

flavor, 164 

household development, 289 

ideal standard, 5 

materials used, 1 

package, 164 

poison, 250 

richness, 164 

standards, 267-271 

trowels, 158 

when removed from freezer, 
134 
Ice-cream-making, a science, 6 

problems, 6 
Ice-cream mixers, 88 
Ice-cream powders, 55 
Ice-cream receipts, 45, 71 

bisque, 73 
. caramel, 72 

chocolate, 72 

coffee, 72 

custards, 76 

fruit, 73 

ices, 78 

lacto, 80 

maple, 72 

milk sherbets, 80 

mousse, 73 

nut, 73 

parfait, 74 

puddings, 75 

punches, 79 

vanilla, 71 

water sherbets, 78 
Ice crushers, 93 
Ice-house, 104 
Iceland moss, 55 
Ice plow, 106 
Ices, 70, 78 

freezing, 144 
Ice shovel, 94 
Ice spud, 94 
Irish moss, 55 



Joseph Burnett Extract Co., 57 
Judging and defects, 163 

Keeping quality, 167 

Lacto, 71, 80 
Lactometer, 198 

Board of Health, 199 

Quevenne, 199 
Laws, 264-271 
Lee, C. C, Hepburn, N. W., 

and Barnhart, F. M., 204 
Legal standards, 267-271 
Lemon extract, 65 

adulteration of, 66 

standard forj 65 
Lemon oil, chemistry of, 66 

preparation of, 65 
License, 266 
Loading platform, 276 
Losses, 262 

Machinery, quality of, 81 
Manhattan pudding, 76 i. 

Maple ice-cream, 72 
Marketing, 246 /f 

Market, location of, 250 i 

Mclnerney, T. J., 18, 174 
Mechanical refrigeration, 111 

absorption system, 116, 122, 
124, 126 

compression system, 116 

cost of operating, 121 

direct expansion system, 118 

evaporating coils, 119 

materials used in, 113 

operating, 120 

parts of, 117 

principles of. 111 
Merrell-Soule Co., 34 
Merrell-Soule process, 35 
Michigan Agricultural Law, 15 
Milk and cream, absorption of 
odors, 14 



INDEX 



301 



Milk and cream, acidity of, 11 

adulterated, 264 

''aged," 12 

bacteria in, 15 

contamination, 21 

neutralization of, 11 

proper care of, 22 

purchase of, 24 

quality of, 11, 13 
Milk, composition of, 23 

standard for, 24 
Milk powder, 33 

standards for, 33 
Milk powder in ice-cream, 37, 40 
Milk products, supply of, 8 

method of securing, 9 
Milk sherbets, 80 
Milk, used, 8 
Misbranded ice-cream, 5 
VLix, 129 

financial viewpoint, 130 

step in preparation of, 131 

temperature of, 133 
Mixers, 88 

Mojonnier tester, 218-240 
Mojonnier over-run tester, 240 
Molds, 15 

brick, 159 

center, 161 
. individual, 161 
Mortensen, M., 69, 139, 142, 143, 

158, 163 
Mousse, 73 

National Association of Ice- 
cream Manufacturers, 3 

Nesselrode pudding, 75 

New Jersey Agricultural Law, 
15 

Nut ice-cream, 73 

Nuts, 50 

Oil traps, 117 
Orange extract, 65, 67 



Orange extract, adulteration of, 

68 

standard for, 67 
Organisms, disease, 11 
Over-run, 134, 139 

controlling, 242 

factors effecting, 139 

to obtain, 143 
Over-run tester, 213, 240 

Pack-cans, 91, 145 
Packing tubs, 262 
Parfait, 74 

Pasteurization, 11, 140, 172 
Peptonizing bacteria, 179 
Perfection freezer, 85 
Plans of factory, 273-275 
Powdered milk processes, 34 
"Price Current," 258 
Price of dairy products, 258 
Progress freezer, 86 
Ptomaine poison, 250 
Pudding, 75 

English plum, 76 

fruit, 76 

Manhattan, 76 

Nesselrode, 75 
Punches, 70, 79 

Refrigeration, 101 

terms used, 101 
Rennet, 56 
Report blanks, 261 
Rice flour, 55 
Rose, Flora, 247 
Ross, H. E., io, 23, 205 
Ross, H. E., Guthrie, E. S., 

Fisk, W. W., 208 
Ross, H. E., and Mclnerney, 

T. J., 183 
Ruche, H. A., 43 

Salesmen, 257 
Sandwich machine, 254 



302 



INDEX 



Sanitary codes, 280-286 
Score card, 163 
Sediment test, 17 
Sherbets, 70, 78, 80 

freezing, 144 
Shipping clerk, 260 
Skimmed -milk, composition, 24 

standard for, 24 
Slush box, 148 
Smoothness, 167 
Soft ice-cream, 263 
SoHds not fat, 200 
Sproule, W. H., 197 
Stabilizer, 2, 51, 95, 132 
Standard ice-cream, 4 
Standardization, 208-212 
Stocking, W. A., Jr., 19 
Sugar, 2, 43, 131, 173 

invert, 43, 46 
Sugar-saving substitutes, 45 
SweU, 134, 139 

Test, acid, 200 

Babcock, 183 

Benkendorf, 213 

hardness, 215 

Mojonnier, 218-240 

viscosity, 208 
Testing, 183 
Thayer, L. O., 295 
Transfer ladles or scoops, 146 



Transferring, 263 , 

Troy, H. C, 183, 207 ^^ 

Tub and can freezer, 83 -^ 

Tubs, 262 

f 
Urner Barry Co., 41 
Utensils, cleaning, 279 

Vacuum pump, 27 

Vanilla beans, 59 

Vanilla beans, curing of, 59 

marketing, 59 

production of, 60 
Vanilla, chemistry of, 63 
Vanilla extract, 57 

adulteration of, 64 

ingredients of, 62 
Vanilla ice-cream, \ 1 
Vanilla plant, 58 
Vanillin, 63 
Viscosity, test for, 208 
Vogt refrigerating machine, 123 

Washburn, R. M., 69, 138, 139, 

142, 163 
Water sherbets, 78 
Wisconsin Agricultural Law, 15, 

264 

Yeasts, 15 



Printed in the United States of America. 



